https://www.mrcorfe.com/Hamble/MCQ/C?Edit=1
11th Sep '25
Multiple Choice 2015-16
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What are the three states of matter?
The three states of matter are solid, liquid and gas.
The three states of matter are solid, liquid and gas. Melting and freezing take place at the melting point, boiling and condensing take place at the boiling point.
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How are the three states of nmatter represented when using solid spheres to represent particles?
When using solid spheres to represent particles, the three states of matter can be represented as follows: Solid - particles packed tightly together and are arranged in a regular pattern. Liquid - particles are close together and arranged in a random way. Gas - particles are far apart and arranged in a random way.
The three states of matter can be represented by a simple model. In this model, particles are represented by small solid spheres.
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What happens to a substance as it changes from a solid to a liquid?
When a substance is changing state from a solid to a liquid, it is melting. In a solid the particles are close together and touching in a fixed pattern. They are vibrating around a fixed point. As the particles are heated they begin to store more internal energy. The particles transfer this internal energy store using a thermal pathway into kinetic energy and therefore move more. In a liquid the particles are still touching but are arranged in a random way and can flow over one another.
Particle theory can help to explain melting, boiling, freezing and condensing.
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Why do different substances have different melting and boiling points?
Different substances have different melting and boiling points because the amount of energy needed to change state from solid to liquid and from liquid to gas depends on the strength of the forces between the particles of the substance. The nature of the particles involved depends on the type of bonding and the structure of the substance. The stronger the forces between the particles the higher the melting point and boiling point of the substance.
The amount of energy needed to change state from solid to liquid and from liquid to gas depends on the strength of the forces between the particles of the substance. The nature of the particles involved depends on the type of bonding and the structure of the substance. The stronger the forces between the particles the higher the melting point and boiling point of the substance.
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What are the limitations to using simple particle models used to represent the different states of matter?
The limitations of the simple particle models used to represent the different states of matter are that in the model there are no forces represented, all particles are represented as spheres and that the spheres are solid.
(HT only) Limitations of the simple model above include that in the model there are no forces, that all particles are represented as spheres and that the spheres are solid.
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What state would substance A be at room temperature (25oC) when substance A has a melting point of -10oC and a boiling point of 55oC?
When substance A has a melting point of -10oC and a boiling point of 55oC, substance A would be a liquid at room temperature as 25oC is greater than the melting point of substance A but lower than its boiling point.
Students should be able to predict the states of substances at different temperatures given appropriate data
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Why does water boil at 100oC rather than 90oC, in terms of bonding and energy transfers?
Water boils at 100oC, rather than 90oC, as the amount of energy needed to break each bond between the water molecules is only reached at 100oC and not at 90oC.
Students should be able to explain the different temperatures at which changes of state occur in terms of energy transfers and types of bonding
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(HT) What are the limitations of the particle theory in relation to changes of state?
(HT) The limitations of particle theory in relation to changes of state are that the particles are represented by solid, inelastic spheres which have no forces between them. It also does not show the bonds between molecules, does not take into account the size of particles and the space between them.
(HT only) explain the limitations of the particle theory in relation to changes of state when particles are represented by solid inelastic spheres which have no forces between them.
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What is the smallest part of an element that can exist?
An atom is the smallest part of an element that can exist.
All substances are made of atoms. An atom is the smallest part of an element that can exist.
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How are atoms of elements represented on the periodic table?
Atoms of each element are represented by a chemical symbol.
Atoms of each element are represented by a chemical symbol, eg O represents an atom of oxygen, Na represents an atom of sodium.
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How many different elements are there?
There are over 100 different elements.
There are about 100 different elements. Elements are shown in the periodic table.
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How are compounds formed?
Compounds are formed from elements by chemical reactions.
Compounds are formed from elements by chemical reactions.
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How can chemical reactions be detected other than through the observation of new substances forming?
Chemical reactions can be measured by a detectable energy change.
Chemical reactions always involve the formation of one or more new substances, and often involve a detectable energy change.
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What is a compound and how is it respresented?
Compounds contain two or more elements chemically combined in fixed proportions and can be represented by formulae using the symbols of the atoms from which they were formed.
Compounds contain two or more elements chemically combined in fixed proportions and can be represented by formulae using the symbols of the atoms from which they were formed.
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What type of reaction is needed to separate a compound into elements?
Compounds can only be separated into elements by chemical reactions.
Compounds can only be separated into elements by chemical reactions.
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How are chemical reactions represented?
Chemical reactions can be represented by word equations or equations using symbols and formulae.
Chemical reactions can be represented by word equations or equations using symbols and formulae.
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What are the names and symbols of elements in Groups 1 and 7?
Group 1: L (Lithium), Na (Sodium), K (Potassium), Rb (Rubidium), Cs (Caesium), Fr (Francium). Group 7: F (Fluorine), Neon (Ne), Argon (Ar), Kr (Krypton), Xe (Xenon), Rn (Radon).
Students will be supplied with a periodic table for the exam and should be able to use the names and symbols of the first 20 elements in the periodic table, the elements in Groups 1 and 7, and other elements in this specification
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What are the names of the following compounds: NaCl, KF, LiBr?
NaCl - sodium chloride, KF - potassium fluoride, LiBr - Lithium bromide.
Name compounds of these elements from given formulae or symbol equations.
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In a chemical equation, what do the symbols (s), (l), (g), and (aq) represent?
In a chemical equation, the following symbols represent the following states: (s) = Solid (l) = Liquid (g) = Gas (aq) = Aqueous solution (dissolved in water)
In chemical equations, the three states of matter are shown as (s), (l) and (g), with (aq) for aqueous solutions.
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What state symbols are added to each part of the chemical equation below? C O2 -> CO2
The state symbols added the each part of the chemical equation is seen below: C (s) O2 (g) -> CO2 (g)
Review from KS3 balancing equations if secure in the naming and symbols of basic elements and compounds.
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What is a mixture?
A mixture consists of two or more elements or compounds not chemically combined together.
A mixture consists of two or more elements or compounds not chemically combined together.
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What happens to the chemical properties of each substance in a mixture?
In a mixture the chemical properties of each substance in the mixture are unchanged.
The chemical properties of each substance in the mixture are unchanged.
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When mixtures are separated by physical processes how does this affect the chemical reactions and substances made?
Mixtures separated by physical processes do not involve chemical reactions and no new substances are made.
Mixtures can be separated by physical processes such as filtration, crystallisation, simple distillation, fractional distillation and chromatography. These physical processes do not involve chemical reactions and no new substances are made.
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How are mixtures separated using filtration?
Mixtures of insoluble solid molcules and liquids can be seperated using filitration. The insoluble solid is unable to pass through filter paper allowing them to be separated from a liquid. For example a when a mixture of sand and water is filtered the sand remains in the filter and the water passes through.
Filtration (review from KS3)
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How are mixtures separated using crystallisation?
Crystallisation can be used to separate a solid that has dissolved in a liquid. The mixture is heated to remove most of the liquid and then left to allow crystals of the solid to form
Crystallisation (review from KS3)
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How are mixtures separated using simple distillation?
Distillation is a process that can be used to separate a pure liquid from a mixture of liquids. It works when the liquids have different boiling points. Distillation is commonly used to separate ethanol - the alcohol in alcoholic drinks - from water.
Simple distillation (review from KS3)
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How are mixtures separated using fractional distillation?
During fractional distillation a mixture is separated into its component parts, or fractions, based on their boiling point. This is achieved by heating them to a temperature at which one or more fractions of the compound will vaporise and condensing them at different temperatures in a distillation column.
fractional distillation
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How are mixtures separated using chromatography?
In chromatography a mixture is passed through a medium in which the components move at different rates allowing separation of the individual components.
chromatography (review from KS3)
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How could we separare a mixture of sand, salt, iron and water into its individual components?
A mixture of sand, salt, iron and water can be seperated using filtration to separate out the insoluble solids (iron and sand) from the solution (salt and water). Iron can be separated from the sand using a magnet. Salt and water can be separated by either evaporation or distillation.
Students should be able to suggest suitable separation and purification techniques for mixtures when given appropriate information.
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What can lead to a scientific model being changed or replace?
New experimental evidence may lead to a scientific model being changed or replaced.
New experimental evidence may lead to a scientific model being changed or replaced. (WS) This historical context provides an opportunity for students to show an understanding of why and describe how scientific methods and theories develop over time.
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What is an atom?
The word atom means indivisible. An atom is the smallest constituent unit of ordinary matter.
Before the discovery of the electron, atoms were thought to be tiny spheres that could not be divided.
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What were the main features of the 'plum pudding' model of the atom?
In the plum pudding model the atom was thought to be a sphere of positive charge with negatively charged electrons dotted around inside it like plums in a pudding.
The discovery of the electron led to the plum pudding model of the atom.
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How did the 'plum pudding' model describe the structure of an atom?
The plum pudding model suggested that the atom is a ball of positive charge with negative electrons embedded in it.
The plum pudding model suggested that the atom is a ball of positive charge with negative electrons embedded in it.
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How did the Rutherford's alpha particle scattering experiment change our understanding of the structure of the atom?
A beam of alpha particles was aimed at very thin gold foil and their passage through the foil detected. The scientists expected the alpha particles to pass straight through the foil, but something else also happened. Some of the alpha particles emerged from the foil at different angles, and some even came straight back. The scientists realised that the positively charged alpha particles were being repelled and deflected by a tiny concentration of positive charge in the atom. As a result of this experiment, the plum pudding model was replaced by the nuclear model of the atom.
The results from the alpha particle scattering experiment led to the conclusion that the mass of an atom was concentrated at the centre (nucleus) and that the nucleus was charged. This nuclear model replaced the plum pudding model.
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What contribution did Niels-Bohr make in furthering our understanding of the structure of the atom.
Niels-Bohr adapted the nuclear model by suggesting that electrons orbit the nucleus at specific distances. The theoretical calculations of Bohr agreed with experimental observations.
Niels Bohr adapted the nuclear model by suggesting that electrons orbit the nucleus at specific distances. The theoretical calculations of Bohr agreed with experimental observations.
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Which subatomic particle gives the nucleus of the atom a positive charge?
Protons give the nucleus of the atom a postive charge, each proton has mass of 1 and a 1 charge.
Later experiments led to the idea that the positive charge of any nucleus could be subdivided into a whole number of smaller particles, each particle having the same amount of positive charge. The name proton was given to these particles.
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What discovery did James Chadwick make that advanced our understanding of the structure of an atom?
James Chadwick provided evidence that the nucleus of an atom was also made of neutrons. Protons were discovered some 20 years prior.
The experimental work of James Chadwick provided the evidence to show the existence of neutrons within the nucleus. This was about 20 years after the nucleus became an accepted scientific idea.
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How did the evidence of alpha particles scattering lead to a change in the atomic model?
The new evidence of alpha particles scattering during the gold leaf experiment lead to a new atomic model as it proved most of the atom was empty space except for a postive charge at the very centre of it.
Students should be able to describe why the new evidence from the scattering experiment led to a change in the atomic model
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Describe the currently accepted structure of the atom
A nucleus composed of protons and neutrons, surrounded by shells of electrons.
Students should be able to describe the difference between the plum pudding model of the atom and the nuclear model of the atom.
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What are the relative electrical charges of each sub-atomic particle?
The relative electrical charges of each sub-atomic particles are: Proton 1 Neutron 0 Electron -1
The relative electrical charges of the particles in atoms are: Proton +1 Neutron 0 Electron -1
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Why do atoms have no overall charge?
Atoms do not have an overall charge as a number of POSITIVE protons will always match the number of NEGATIVE electrons.
Atoms have no overall electrical charge.
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If an atom has 9 protons, how many electrons would it have?
If an atom has 9 protons it would have 9 electrons.
In an atom, the number of electrons is equal to the number of protons in the nucleus.
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What does the atomic number of an element tell us?
The atomic number tells us the number of protons found in an atom of that element.
The number of protons in an atom of an element is its atomic number.
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What do all atoms of a particular element have in common?
Atoms of the same element all have the same number of protons.
All atoms of a particular element have the same number of protons.
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What are the differences between an atom of Nitrogen and an atom of Carbon. What is it that makes them unique elements?
An atom of carbon has: Protons= 6 Electrons= 6 Neutrons= 6. An atom of Nitrogen has: Protons= 7 Electrons= 7 Neutrons= 7. It is the differing number of protons which makes them unique elements.
Atoms of different elements have different numbers of protons.
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How does the current nuclear model describe an atom?
The nuclear model shows that an atom is made of a small nucleus of positive protons and neutral neutrons, it also has negatively charged electrons orbiting it in energy levels.
Students should be able to use the nuclear model to describe atoms.
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How large is the radius of the nucleus of an atom in comparison to its total radius?
The radius of the nucleus of an atom compared to the total atoms radius is 1/10 000 of that of the atom (about 1 x 10 to the power -14 m).
The radius of a nucleus is less than 1/10 000 of that of the atom (about 1 x 10-14 m).
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Where is the majority of the mass of the atom found?
The majority of the mass of the atom is found within the nucleus and is made up of protons and neutrons. Electrons have a negligible mass.
Almost all of the mass of an atom is in the nucleus.
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What are the relative masses of each subatomic particle (proton, neutron and electron)?
The relative masses of the subatomic particles are: Proton = 1 Neutron = 1 Electron = negligible (very small)
The relative masses of protons, neutrons and electrons are: Proton 1 Neutron 1 Electron Very small
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What does the mass number of an atom tell us about that atom?
The mass number tells us the total number of protons and neutrons within that atom.
The sum of the protons and neutrons in an atom is its mass number.
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What is an isotope?
An isotope is an atom of the same element with differing numbers of neutrons.
Atoms of the same element can have different numbers of neutrons; these atoms are called isotopes of that element.
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What do the individual tiles of the periodic table tell us?
The individual tiles of the periodic table tell us the chemical symbol, Mass number, Atomic (Proton) number
Atoms can be represented as shown in this example: (periodic table tile for sodium with mass and atomic number)
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Calculate the number of protons, neutrons and electrons in an atom of Cobalt. Mass number = 59 and Atomic number = 27
The total number of subatomic particles in cobalk are: Protons: 27 Electrons: 27 Neutrons: 32
Students should be able to calculate the numbers of protons, neutrons and electrons in an atom or ion, given its atomic number and mass number.
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How large are atoms? a) 1 × 10-6 m b) 1 × 10-8 m c) 1 × 10-10 m
The size of atoms are 1 × 10-10 m
Students should be able to relate size and scale of atoms to objects in the physical world.
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Why does chlorine have a mass number of 35.5?
The relative atomic mass of an element is an average value that takes account of the abundance of the isotopes of the element. Chlorine exists as 75% Cl35 and 25% Cl37, an average of this is taken.
The relative atomic mass of an element is an average value that takes account of the abundance of the isotopes of the element.
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What is the relative atomic mass of bromine where there are two isotopes of Bromine, 50% Br-79 and 50% Br-81?
The relative atomic mass of bromine is 80, since (79 x 50) + (81 x 50) / 100 = 80.
Students should be able to calculate the relative atomic mass of an element given the percentage abundance of its isotopes.
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What is the maximum number of electrons that can be held by each of the three inner most shells?
The maximum number of electrons are 2 in the inner most shell, 8 in the second shell and 8 in the third shell.
The electrons in an atom occupy the lowest available energy levels (innermost available shells).
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What would a diagram of the electron structure of an atom of carbon look like?
A diagram of the electronic structure of carbon would have 2 electrons on inner most shell, 4 on the second shell.
The electronic structure of an atom can be represented by numbers or by a diagram. For example, the electronic structure of sodium is 2,8,1 or (electron arrangement using dot-and-cross diagram) showing two electrons in the lowest energy level, eight in the second energy level and one in the third energy level.
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Why is carbon found in group 4 of the periodic table?
Carbon is found in group 4 because there are 4 electrons in its outermost shell.
(WS) Students should be able to represent the electronic structures of the first twenty elements of the periodic table in both forms.
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How big is the total radius of an average atom?
The total radius of an average atom is 0.1 nm (1 x 10-10 m).
Atoms are very small, having a radius of about 0.1 nm (1 x 10-10 m).
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How are elements ordered in the periodic table?
The elements in the periodic table are arranged in order of atomic (proton) number and so that elements with similar properties are in columns, known as groups. The table is called a periodic table because similar properties occur at regular intervals.
The elements in the periodic table are arranged in order of atomic (proton) number and so that elements with similar properties are in columns, known as groups. The table is called a periodic table because similar properties occur at regular intervals.
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Metals react to form __________ charged ions
Metals react to form POSITIVELY charged ions
Elements that react to form positive ions are metals.
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In terms of electron structure, how are elements in the same group similar?
Elements in the same group in the periodic table have the same number of electrons in their outer shell (outer electrons) and this gives them similar chemical properties.
Elements in the same group in the periodic table have the same number of electrons in their outer shell (outer electrons) and this gives them similar chemical properties.
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Non-metals react to form __________ charged ions
Non-metals react to form NEGATIVELY charged ions
Elements that do not form positive ions are non-metals.
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What does the group and period of an element tell us about its electron structure?
Period = Total number of electron shells. Group = Total number of electrons found in the outermost shell
Students should be able to explain how the position of an element in the periodic table is related to the arrangement of electrons in its atoms and hence to its atomic number
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Are there more metals or non-metal elements on the periodic table?
The majority of elements are metals.
The majority of elements are metals.
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Predict how the reactivity of caesium would compare to lithium
Caesium would be far more reactive than lithium because it is further down group 1 so it experiences more shielding from the nucleus
Students should be able to predict possible reactions and probable reactivity of elements from their positions in the periodic table.
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How were elements in early periodic tables ordered?
By atomic mass
Before the discovery of protons, neutrons and electrons, scientists attempted to classify the elements by arranging them in order of their atomic weights.
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Why were early attempts at ordering the periodic table by atomic mass unsuccessful?
As this caused certain elements to be incorrectly placed in groups with elements with very different propertiesno.
The early periodic tables were incomplete and some elements were placed in inappropriate groups if the strict order of atomic weights was followed.
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How did Mendeleev predict the existence of several undiscovered elements when designing his periodic table?
He identified where there was no existing element that fit the pattern of his periodic table, so left gaps in for them.
Mendeleev overcame some of the problems by leaving gaps for elements that he thought had not been discovered and in some places changed the order based on atomic weights.
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How are metals and non-metal elements arranged on the periodic table
Metals are found to the left and towards the bottom of the periodic table. Non-metals are found towards the right and top of the periodic table.
Metals are found to the left and towards the bottom of the periodic table. Non-metals are found towards the right and top of the periodic table.
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What steps were involved in the development of the periodic table?
1. Groups of three elements with similar properties called triads. 2. More accurate atomic weights 3. Newlands table in atomic weight (law of octaves) 4. Mendeleev who left gaps putting them in groups with similar properties
Students should be able to describe these steps in the development of the periodic table.
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Which group of the periodic table are also named the nobel gases?
Group 0
The elements in Group 0 of the periodic table are called the noble gases.
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Describe in terms of electron structure as to why all of the nobel gases are unreactive
They all have a full outer shell of electrons, as a result do not easily form molecules
The elements in Group 0 of the periodic table are unreactive and do not easily form molecules because their atoms have stable arrangements of electrons.
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What is the same about the electron structure for all elements in Group 0 (noble gases)?
All elements in Group 0 (noble gases) have a full outer shell of electrons.
The noble gases have eight electrons in their outer shell, except for helium, which has only two electrons.
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Describe the trend in boiling point down group 0
Boiling points increase with relative atomic mass (as you go down the group)
The boiling points of the noble gases increase with increasing relative atomic mass (going down the group).
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What is the common name given to the group 1 elements?
Alkali metals
The elements in Group 1 of the periodic table are known as the alkali metals and have characteristic properties because of the single electron in their outer shell.
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Give 4 common properties of transition metal elements.
Heat conductor, Electrical conductor, Lustrous (shiny), Dense, High melting and boiling point, High tensile strength, Strong, Hard
Students should be able to explain the differences between metals and non-metals on the basis of their characteristic physical and chemical properties. This links to Group 0, Group 1, Group 7 and Bonding, structure and the properties of matter
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Write a word equation for the reaction of sodium with chlorine.
Sodium + Chlorine -> Sodium Chloride
Students should be able to describe the reactions of the first three alkali metals with oxygen, chlorine and water.
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Describe the trend in reactivity in group 1 as you go down the group
Reactivity of elements in group 1 increases as you go down the group (Lithium = least reactive, Francium = most reactive)
In Group 1, the reactivity of the elements increases going down the group.
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For elements in Group 1, what do the properties depend on?
Properties of the elements in Group 1 depend on the outer shell of electrons of the atoms
Students should be able to explain how properties of the elements in Group 1 depend on the outer shell of electrons of the atoms
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Explain why elements become more reactive the further you go down group 1
Elements in group 1 react by giving up their outermost electron. The further down the group you go the weaker the attraction between the nucleus of the atom and the outermost electron, as well as a greater amount of shielding. Therefore the electron is given up more easily.
Students should be able to predict properties from given trends down the group.
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What are the transition elements?
Metals with similar properties which are different from those of the elements in Group 1.
The transition elements are metals with similar properties which are different from those of the elements in Group 1.
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Compare the properties of transition metal elements with those of the group 1 elements.
Group 1 metals are soft, highly reactive to oxygen and water, form alkali solutions, are less dense than group 2 metals. Group 2 metals are harder, less reactive.
Students should be able to describe the difference compared with Group 1 in melting points, densities, strength, hardness and reactivity with oxygen, water and halogens.
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Give examples of 3 transition metals
Any three from the transition block eg. Cr, Mn, Fe, Co, Ni, Cu.
Students should be able to exemplify these general properties by reference to Cr, Mn, Fe, Co, Ni, Cu.
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What is the common name given to the group 7 elements?
The halogens
The elements in Group 7 of the periodic table are known as the halogens and have similar reactions because they all have seven electrons in their outer shell.
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Describe the trend in boiling point and melting point of elements as you go down group 7?
As you go down group 7, the melting and boiling points of the elements increases.
In Group 7, the further down the group an element is the higher its relative molecular mass, melting point and boiling point.
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Describe the trend in reactivity of elements as you go down group 7?
As you go down group 7, the reactivity of the elements decreases.
In Group 7, the reactivity of the elements decreases going down the group.
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Write a word equation for the reaction between sodium chloride and fluorine. What type of reaction is this?
Sodium chloride Fluorine -> Sodium Fluoride Chlorine. This is a displacement reaction as the more reactive halogen displaces the less reactive halogen from its compound.
A more reactive halogen can displace a less reactive halogen from an aqueous solution of its salt.
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In terms of electron structure, whAt do all group 7 elements share in common?
They all have 7 electrons in their outermost shell
Students should be able to explain how properties of the elements in Group 7 depend on the outer shell of electrons of the atoms
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List the elements of group 7 in order of reactivity.
Fluorine, Chlorine, Bromine, Iodine, Astatine
Students should be able to predict properties from given trends down the group.
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Many transition elements are also useful as catalysts. What is a catalyst?
A catalyst is a substance which speeds up a chemical reaction without being used up itself.
Many transition elements have ions with different charges, form coloured compounds and are useful as catalysts.
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List the general properties of compounds of transition elements
Students should be able to exemplify these general properties by reference to compounds of Cr, Mn, Fe, Co, Ni, Cu.
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How can different atoms interact with each to gain a full outer shell of electrons.
Atoms can gain, lose or share electrons. (Metals on their own will delocalise their outer electron(s).)
There are three types of strong chemical bonds: ionic, covalent and metallic. ALTERNATIVE activity - independent thinking.
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What are the three types of chemical bonding?
Ionic, Metallic and Covalent
There are three types of strong chemical bonds: ionic, covalent and metallic.
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Name the type of attraction between particles in an ionic bond
Electrostatic attraction (attraction between oppositely charged particles)
For ionic bonding the particles are oppositely charged ions.
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In terms of electrons, how are covalent bonds formed?
When two non-metal atoms share electrons to form a bond
For covalent bonding the particles are atoms which share pairs of electrons.
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Metallic bonds have delocalised electrons. What are delocalised electrons?
Electrons in a molecule, ion or solid metal that are not associated with a single atom
For metallic bonding the particles are atoms which share delocalised electrons.
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Ionic bonding occurs in compounds formed from ________ combined with ___________.
Ionic bonding occurs in compounds formed from METALS combined with NON-METALS.
Ionic bonding occurs in compounds formed from metals combined with non-metals.
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Covalent bonding occurs when _____________ atoms bond together.
Covalent bonding occurs when NON-METAL atoms bond together.
Covalent bonding occurs in most non-metallic elements and in compounds of non-metals.
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Metallic bonding occurs between atoms of __________ elements.
Metallic bonding occurs between atoms of METAL elements.
Metallic bonding occurs in metallic elements and alloys.
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What is chemical bonding?
chemical bonding is where atoms are held together because of electrostatic forces caused by the transfer or sharing of electrons.
Students should be able to explain chemical bonding in terms of electrostatic forces and the transfer or sharing of electrons.
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Describe the transfer of electrons in an ionic bond
Electrons are donated from the metal element in order to complete the outer shell of the non-metal element
When a metal atom reacts with a non-metal atom, electrons in the outer shell of the metal atom are transferred.
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When a metal atom become an ion it loses electrons. How does this effect its charge?
It becomes a positively charged ion.
Metal atoms lose electrons to become positively charged ions.
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When a non-metal atom bonds ionically it gains electrons. How does this effect its charge?
It becomes a negatively charged ion.
Non-metal atoms gain electrons to become negatively charged ions.
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What is the electronic structure of ions produced by group 1,2 metals and group 6,7 non metals?
They have full outside shells of electrons giving them a stable electronic configuration, the same as a noble gas.
The ions produced by metals in Groups 1 and 2 and by non-metals in Groups 6 and 7 have the electronic structure of a noble gas (Group 0).
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How could you show the formation of an ionic compound using a dot and cross diagram?
Showing outer electrons only. Crosses for one element and dots for the other. Show transfer of electrons on shell. Use brackets to show the overall charge of the ions formed.
The electron transfer during the formation of an ionic compound can be represented by a dot and cross diagram. E.g. for sodium chloride.
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Draw a dot cross diagram to show the ionic bond in sodium chloride.
Diagram: Sodium - Electron strucuture represented in square brackets, with a 1 charge on the top right outside the bracket. . It's one outer shell electron removed. Chlorine - Electron strucuture represented in square brackets, with a -1 charge on the top right outside the bracket. One extra electron represented as either a dot or cross shown to represent the electron gained from sodium.
Students should be able to draw dot and cross diagrams for ionic compounds formed by metals in Groups 1 and 2 with non-metals in Groups 6 and 7.
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What charge do ions of elements from the following groups form 1) Group 1 2) Group 2 3) Group 6 4) Group 7
1) Group 1 = +1 ion 2) Group 2 = +2 ion 3) Group 6 = -2 ion 4) Group 7 = -1 ion
The charge on the ions produced by metals in Groups 1 and 2 and by non-metals in Groups 6 and 7 relates to the group number of the element in the periodic table.
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Explain why potassium chloride is KCl but potassium oxide is K2O
The overall charge of an ionic compound will always be neutral. Potassium forms an ion with a 1 charge, so will bond in a 1:1 ratio chlorine as chlorine forms a -1 ion. Oxygen on the other hand forms a -2 ion, so for each Oxygen 2 potassiums would be needed to neutralise the charge.
Students should be able to work out the charge on the ions of metals and non-metals from the group number of the element, limited to the metals in Groups 1 and 2, and non-metals in Groups 6 and 7.
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What is an ionic compound?
A giant structure of ions
An ionic compound is a giant structure of ions.
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What do we call the attraction between oppositely charged ions?
Electrostatic attraction
Ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions.
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Describe the structure of a giant ionic lattice.
It is a 'lattice' because the arrangement is a regular one and 'giant' because the arrangement is repeated many times with large numbers of ions.
These forces act in all directions in the lattice: this is called ionic bonding.
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What two models can be used to represent giant ionic structures?
Ball and stick and charged ion ionic lattice
The structure of sodium chloride can be represented in the following forms: ball and stick giant lattice and charged ion ionic lattice.
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Give a limitation of each the ball and stick model and charged ion ionic lattice models for representing ionic bonds.
Ball and stick model: - The ions are actually packed closer together - Gives a false image of bond direction when is only electrostatic attraction Charged ion ionic lattice model: - Difficult to see the arrangement of ions in 3D.
Students should be able to describe the limitations of using dot and cross, ball and stick, two and three-dimensional diagrams to represent a giant ionic structure.
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Determine the empirical formulae of a compound given the ions: a) Na+ and N3- b) Al3+ and O2-
a) Na3N b) Al2O3
Students should be able to work out the empirical formula of an ionic compound from a given model or diagram that shows the ions in the structure.
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Draw out a dot cross diagram to show the ionic bond formed in the compound sodium chloride.
The sodium ion has an electon pattern of (2,8) and is represented in square brackets with a + charge in the top right corner, as a consequence of having lost an electron from its outer shell. This is then placed next to the chloride ion, which has an electron pattern of (2,8,8) and is also represented in square bracket, but with a - charge in the top right corner, due to it gaining an electron.
Students should be familiar with the structure of sodium chloride but do not need to know the structures of other ionic compounds.
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What are covalent bonds?
Strong bonds that form when atoms share pairs of electrons
When atoms share pairs of electrons, they form covalent bonds. These bonds between atoms are strong.
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What type of substances have covalent bonds?
small molecules
Covalently bonded substances may consist of small molecules.
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What are the names of the following substances CO2 H2O H2 Cl2
Carbon dioxide water hydrogen chlroine
Students should be able to recognise common substances that consist of small molecules from their chemical formula.
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Give an example of large molecules with covalent bonds
Polymers
Some covalently bonded substances have very large molecules, such as polymers.
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Give two examples of substances that have giant covalent structures
diamond graphite silicon dioxide
Some covalently bonded substances have giant covalent structures, such as diamond and silicon dioxide.
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List three ways to represent covalent bonds in molecules
dot and cross diagrams ball and stick diagrams display formula
The covalent bonds in molecules and giant structures can be represented in the following forms: using dot-and-cross diagram, ball-and-stick diagram or displayed formula)
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How are polymers commonly represented?
Polymers can be represented using displayed formulae, where n is a large number.
Polymers can be represented using displayed formulae, where n is a large number.
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Draw dot and cross diagrams for the molecules of hydrogen, chlorine, oxygen, nitrogen, hydrogen chloride, water, ammonia and methane look like?
Students should be able to draw dot and cross diagrams for the molecules of hydrogen, chlorine, oxygen, nitrogen, hydrogen chloride, water, ammonia and methane
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How would you draw a single covalent bond?
single line between atoms
Students should be able to represent the covalent bonds in small molecules, in the repeating units of polymers and in part of giant covalent structures, using a line to represent a single bond
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What are the limitations of using dot and cross, ball and stick, 2D and 3D diagrams to represent substances?
dot and cross, ball and stick do not show orginatation in space.
Students should be able to describe the limitations of using dot and cross, ball and stick, two and three-dimensional diagrams to represent molecules or giant structures
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What is the structure of a metal like?
Metals consist of giant structures of atoms arranged in a regular pattern.
Metals consist of giant structures of atoms arranged in a regular pattern.
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How are the electrons in the outer shell of metal atoms arranged?
The electrons in the outer shell of metal atoms are delocalised and so are free to move through the whole structure.
The electrons in the outer shell of metal atoms are delocalised and so are free to move through the whole structure.
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Why are metallic bonds so strong?
The sharing of delocalised electrons gives rise to strong metallic bonds. The bonding in metals may be represented in the following form: (diagram)
The sharing of delocalised electrons gives rise to strong metallic bonds. The bonding in metals may be represented in the following form: (diagram)
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Describe the structure of metallic bonding?
positive atoms surrounded by negatively charged delocalised electrons
Students should be able to recognise substances as metallic giant structures from diagrams showing their bonding.
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When compared with the properties of materials, do atoms have the same bulk properties?
Atoms themselves do not have the bulk properties of materials.
Students should be able to recognise that atoms themselves do not have the bulk properties of materials
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1. How do a metal and non-metal bond? 2. How do two non-metals bond?
1. ionic bonding by losing/gaining electrons. 2. covalent bonding by sharing pairs of electrons.
Students should be able to describe and explain the bonding in ionic and simple covalent bonding.
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Why are metals good conductors of electricity?
Metals are good conductors of electricity because the delocalised electrons in the metal carry electrical charge through the metal.
Metals are good conductors of electricity because the delocalised electrons in the metal carry electrical charge through the metal.
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In pure metals atoms are arranged in layers. What property does this give them?
It causes them to be malleable (means they can be bent and shaped).
In pure metals, atoms are arranged in layers, which allows metals to be bent and shaped.
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Why are metals good conductors of thermal energy?
Metals are good conductors of thermal energy because energy is transferred by the delocalised electrons.
Metals are good conductors of thermal energy because energy is transferred by the delocalised electrons.
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Why are pure metals often mixed with other metals or carbon?
Pure metals are too soft for many uses and so are mixed with other metals to make alloys which are harder.
Pure metals are too soft for many uses and so are mixed with other metals to make alloys which are harder.
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Why are alloys harder than pure metals?
Alloys are harder than pure metals as alloys contain atoms of different sizes. This causes distortion of the layers of atoms compared with the regular struccture of a pure metal. The regular structure in a pure metal allows the layers to slide over one another.
Students should be able to explain why alloys are harder than pure metals in terms of distortion of the layers of atoms in the structure of a pure metal.
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Describe the structure of an ionic compound?
Ionic compounds have regular structures (giant ionic lattices) in which there are strong electrostatic forces of attraction in all directions between oppositely charged ions.
Ionic compounds have regular structures (giant ionic lattices) in which there are strong electrostatic forces of attraction in all directions between oppositely charged ions.
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Explain why ionic compounds have high melting and boiling points?
These compounds have high melting points and high boiling points because of the large amounts of energy needed to break the many strong bonds.
These compounds have high melting points and high boiling points because of the large amounts of energy needed to break the many strong bonds.
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Under what conditions are ionic compounds able to conduct electricity?
When melted or dissolved in water, ionic compounds conduct electricity because the ions are free to move and so charge can flow.
When melted or dissolved in water, ionic compounds conduct electricity because the ions are free to move and so charge can flow.
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What are the structures of different ionic compounds?
Need to know the structure of sodium chloride.
Knowledge of the structures of specific ionic compounds other than sodium chloride is not required.
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Substances that consist of small molecules are most commonly which states of matter at room temperature?
They tend to have lower boiling points, meaning they commonly exist at room temperature either as gases or liquids.
Substances that consist of small molecules are usually gases or liquids that have relatively low melting points and boiling points.
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How does the size of a molecule affect the size of its intermolecular force?
The larger the molecule the greater the size of its intermolecular force. Hence larger molecules tend to have higher melting and boiling points.
The intermolecular forces increase with the size of the molecules, so larger molecules have higher melting and boiling points.
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Explain why substances that consist of small molecules often have low boiling and melting points
Smaller molecules tend to have weaker intermolecular forces of attraction. This means only small amounts of energy are required to overcome the intermolecular forces that hold molecules of that substance together.
These substances have only weak forces between the molecules (intermolecular forces).
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Why are covalent compounds unable to conduct electricity?
Because covalent molecules carry no overall charge
These substances do not conduct electricity because the molecules do not have an overall electric charge.
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What is the difference between intermolecular forces and intramolecular forces?
Intermolecular forces are the forces of attraction between different molecules of the same substance. Intramolecular forces are the bonds between atoms of the same molecule eg. ionic or covalent bonds.
It is these intermolecular forces that are overcome, not the covalent bonds, when the substance melts or boils.
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Which is stronger: A covalent bond or intermolecular force?
Intermolecular forces are weak when compared with covalent bonds and explain the bulk properties of molecular substances.
Students should be able to use the idea that intermolecular forces are weak compared with covalent bonds to explain the bulk properties of molecular substances.
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Why is diamond so hard, in terms of its structure and bonding?
each carbon atom forms four covalent bonds with other carbon atoms in a giant covalent structure, so diamond is very hard, has a very high melting point and does not conduct electricity.
Students should be able to explain the properties of diamond in terms of its structure and bonding.
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Why do metals tend to have high melting and boiling points?
Metals have giant structures of atoms with strong metallic bonding. This means that most metals have high melting and boiling points.
Metals have giant structures of atoms with strong metallic bonding. This means that most metals have high melting and boiling points.
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How many bonds does each carbon atom form in graphite and how does this impact it's structure?
In graphite, each carbon atom forms three covalent bonds with three other carbon atoms, forming layers of hexagonal rings which have no covalent bonds between the layers.
In graphite, each carbon atom forms three covalent bonds with three other carbon atoms, forming layers of hexagonal rings which have no covalent bonds between the layers.
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What happens to the spare electron that remains unused in a covalent bond in graphite?
It becomes delocalised (shared between atoms)
In graphite, one electron from each carbon atom is delocalised.
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Why do giant covalent structures have very high melting and boiling points?
Their covalent bonds must be overcome in order for them to melt or boil, meaning large amounts of energy are required..
These bonds must be overcome to melt or boil these substances.
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Why is graphite soft and slippery?
Because individual layer of graphite are only held together by weak intermolecular forces, allowing them to easily slide away from each other.
Students should be able to explain the properties of graphite in terms of its structure and bonding.
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How is graphite similar to metals?
Graphite is similar to metals in that is has delocalised electrons.
Students should know that graphite is similar to metals in that it has delocalised electrons.
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What makes graphene useful in electronics and composites?
Graphene is a single layer of graphite and has properties that make it useful in electronics and composites.
Graphene is a single layer of graphite and has properties that make it useful in electronics and composites.
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What are the properties of carbon nanotubes and what do their properties make them useful for?
Carbon nanotubes are cylindrical fullerenes with very high length to diameter ratios. Their properties make them useful for nanotechnology, electronics and materials.
Carbon nanotubes are cylindrical fullerenes with very high length to diameter ratios. Their properties make them useful for nanotechnology, electronics and materials.
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What are the properties of graphene in terms of its structure and bonding?
- One atom thick, so is 2D in structure. - Strong, as each layer of graphene is held together by strong covalent bonds. - Able to conduct electricity and heat, due to each carbon giving up a delocalised electron.
Students should be able to explain the properties of graphene in terms of its structure and bonding.
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What are fullerenes and what is their structure?
Fullerenes are molecules of carbon atoms with hollow shapes. The structure of fullerenes is based on hexagonal rings of carbon atoms but they may also contain rings with five or seven carbon atoms.
Fullerenes are molecules of carbon atoms with hollow shapes. The structure of fullerenes is based on hexagonal rings of carbon atoms but they may also contain rings with five or seven carbon atoms.
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Name three uses of fullerenes?
Fullerenes can be used as carbon nanotubes to reinforce graphite in tennis rackets, semiconductors in electrical circuits, and as nanotubes as a container from transporting a drug in the body.
Students should be able to give examples of the uses of fullerenes, including carbon nanotubes.
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Diamond, graphite and fullerenes are all examples of what type of structure?
Diamond, graphite and fullerenes are all examples of giant covalent structures
Substances that consist of giant covalent structures are solids with very high melting points.
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How many bonds can an individual atom of carbon form? How many bonds does each carbon form in an atom of a) Diamond b) Graphite
A single carbon atom can form a maximum of four possible bonds. a) In diamond each carbon atom is covalently bonded to 4 other carbon atoms. b) In graphite each carbon atom is covalently bonded to 3 other carbon atoms.
In diamond, each carbon atom forms four covalent bonds with other carbon atoms in a giant covalent structure, so diamond is very hard, has a very high melting point and does not conduct electricity.
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Molecules of diamond, graphite and fullerenes are all held together by what type of bonds?
Covalent bonds
All of the atoms in these structures are linked to other atoms by strong covalent bonds.
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Which giant covalent structures are made only from carbon?
Diamond and graphite (forms of carbon) and silicon dioxide (silica) are examples of giant covalent structures.
Diamond and graphite (forms of carbon) and silicon dioxide (silica) are examples of giant covalent structures.
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What was the first fullerene to be discovered and what is its shape?
The first fullerene to be discovered was Buckminsterfullerene (C60) which has a spherical shape.
The first fullerene to be discovered was Buckminsterfullerene (C60) which has a spherical shape.
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What sort of structures does nanoscience refer to?
Nanoscience refers to structures that are 1-100 nm in size, of the order of a few hundred atoms.
Nanoscience refers to structures that are 1?100 nm in size, of the order of a few hundred atoms.
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What is the size of a fine particle and which is smaller, nanoparticles or fine particles?
Nanoparticles, are smaller than fine particles (PM2.5), which have diameters between 100 and 2500 nm (1 x 10-7 m and 2.5 x 10-6 m).
Nanoparticles, are smaller than fine particles (PM2.5), which have diameters between 100 and 2500 nm (1 x 10-7 m and 2.5 x 10-6 m).
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What is the diameter of coarse particles, such as dust?
Coarse particles (PM10) have diameters between 1 x 10-5 m and 2.5 x 10-6 m. Coarse particles are often referred to as dust.
Coarse particles (PM10) have diameters between 1 x 10-5 m and 2.5 x 10-6 m. Coarse particles are often referred to as dust.
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What happens to the size of the surface area to volume ratio of a cube is you decrease the size of the sides by a factor or 10?
As the side of cube decreases by a factor of 10 the surface area to volume ratio increases by a factor of 10.
As the side of cube decreases by a factor of 10 the surface area to volume ratio increases by a factor of 10.
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Why are the properties of nanoparticles different from those for the same materials in bulk?
Nanoparticles may have properties different from those for the same materials in bulk because of their high surface area to volume ratio. It may also mean that smaller quantities are needed to be effective than for materials with normal particle sizes.
Nanoparticles may have properties different from those for the same materials in bulk because of their high surface area to volume ratio. It may also mean that smaller quantities are needed to be effective than for materials with normal particle sizes.
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How do nanoparticles compare in size to individual atoms?
Nanoparticles are made of up to 1000 atoms or molecules, therefore their size is larger than that of an atom.
Students should be able to compare ?nano? dimensions to typical dimensions of atoms and molecules.
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What are the main applications of nanoparticles?
Nanoparticles have many applications in medicine, in electronics, in cosmetics and sun creams, as deodorants, and as catalysts.
Nanoparticles have many applications in medicine, in electronics, in cosmetics and sun creams, as deodorants, and as catalysts. New applications for nanoparticulate materials are an important area of research.
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What are the advantages and disadvantages of using nanoparticles?
The advantages of nanoparticles are endless as they link to many new technilogies both commercially and medically however there are disadvantages as well. There are some concerns that nanoparticles may be toxic to people. They may be able to enter the brain from the bloodstream and cause harm. Some people think more tests should take place before nanoparticles of a material are used on a wider scale.
Students should consider advantages and disadvantages of the applications of these nanoparticulate materials, but do not need to know specific examples or properties other than those specified.
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What sort of molecules are polymers?
Polymers are very large molecules.
Polymers are very large molecules.
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What two monomers form polyester?
ethane diol and hexanedioic acid polymerise to produce a polyester.
For example: ethane diol and hexanedioic acid polymerise to produce a polyester.
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What type of bond links individual monomers together when forming a polymer?
The atoms in the polymer molecules are linked to other atoms by strong covalent bonds.
The atoms in the polymer molecules are linked to other atoms by strong covalent bonds.
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What type of hydrocarbons are used to make polymers?
Alkenes can be used to make polymers such as poly(ethene) and poly(propene) by addition polymerisation.
Alkenes can be used to make polymers such as poly(ethene) and poly(propene) by addition polymerisation. Use models to represent addition polymerisation.
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Why are polymers solids at room temperature?
The intermolecular forces between polymer molecules are relatively strong and so these substances are solids at room temperature.(Remember the greater the size of a molecule the greater the strength its intermolecular forces)
The intermolecular forces between polymer molecules are relatively strong and so these substances are solids at room temperature.
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What happens in an addition polymerisation reaction?
In addition polymerisation reactions, many small molecules (monomers) join together to form very large molecules (polymers).
In addition polymerisation reactions, many small molecules (monomers) join together to form very large molecules (polymers).
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How is a polymer of poly(ethene) produced from ethene? (Show using a diagram)
A polymer of poly(ethene) can be made by many monomers of ethene joining together to make a long chain of polymers. The diagram would show a C=C in the monomer but only a single bond in the polymer e.g. nCH2=CH2 --> [-CH2CH2-]n
For example (displayed formula showing ethene monomer becoming poly(ethene)).
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(Chem only) How is the structure of the repeated unit of an addition polymer related to the monomer?
In addition polymers the repeating unit has the same atoms as the monomer because no other molecule is formed in the reaction.
In addition polymers the repeating unit has the same atoms as the monomer because no other molecule is formed in the reaction.
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(Chem only) How can you identify if you have a polymer or a monomer structure?
addition polymers and monomers can be identified from diagrams by the presence of the functional group C=C in the monomers
Students should be able to recognise addition polymers and monomers from diagrams in the forms shown and from the presence of the functional group C=C in the monomers
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(Chem only) What occurs during a condensation polymersiation reaction?
When monomers with two functional groups react they join together, usually losing small molecules such as water, and so the reactions are called condensation reactions.
When these types of monomers react they join together, usually losing small molecules such as water, and so the reactions are called condensation reactions. Use models to represent condensation polymerisation.
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(Chem only) How many functional groups does each monomer have in the simplest condensation polymerisation reactions?
The simplest polymers are produced from two different monomers with two of the same functional groups on each monomer.
The simplest polymers are produced from two different monomers with two of the same functional groups on each monomer.
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(Chem only) What are the basic principles of condensation polymersiation? (refer to functional groups and repeating units in your answer)
The basic principles of condensation polymerisation are that each monomer has two functional groups and the repeat units are made up of at least two different monomers in alternating sequence
Students should be able to explain the basic principles of condensation polymerisation by reference to the functional groups in the monomers and the repeating units in the polymers.
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(Chem only) When does condensation polymerisation occur?
Condensation polymerisation involves monomers with two functional groups.
Condensation polymerisation involves monomers with two functional groups.
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(Chem only) What are the monomers that form the following naturally occuring polymers? 1. proteins 2. starch 3. cellulose
(HT only) The monomers that form the naturally occuring polymers are: 1. proteins = amino acids 2. starch = glucose 3. cellulose = glucose
Students should be able to name the types of monomers from which these naturally occurring polymers are made. (HT only)
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(Chem only) What type of polymerisation reaction occurs when amino acids react to form polypeptides? (Include a reason why)
(HT only) Amino acids react by condensation polymerisation to produce polypeptides, this is because amino acids have two different functional groups in one molecule.
Amino acids have two different functional groups in a molecule. Amino acids react by condensation polymerisation to produce polypeptides. (HT only)
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(Chem only) What would the equation looks like for the polymerisation of glycine?
(HT only) n NCH COOH --> [-HNCH2COO-]n H2O.
For example: glycine is H NCH COOH and polymerises to produce the polypeptide (-HNCH2COO-) and n H2O. (HT only)
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(Chem only) How are proteins an example of a condensation polymer?
(HT only) Proteins are an example of a condensation polymer because Different amino acids (with two functional groups) can be combined in the same chain to produce proteins.
Different amino acids can be combined in the same chain to produce proteins. (HT only)
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(Chem only) What is DNA and what is its function?
(HT only) DNA (deoxyribonucleic acid) is a large molecule essential for life. DNA encodes genetic instructions for the development and functioning of living organisms and viruses.
DNA (deoxyribonucleic acid) is a large molecule essential for life. DNA encodes genetic instructions for the development and functioning of living organisms and viruses. (HT only)
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(Chem only) Why is the structure of DNA described as a polymer?
(HT only) Most DNA molecules are two polymer chains, made from four different monomers called nucleotides, in the form of a double helix.
Most DNA molecules are two polymer chains, made from four different monomers called nucleotides, in the form of a double helix. (HT only)
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(Chem only) What are the other naturally occuring polymers that are important for life processes?
(HT only) Other naturally occurring polymers important for life include proteins, starch and cellulose.
Other naturally occurring polymers important for life include proteins, starch and cellulose. (HT only)
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What is the law of the conservation of mass?
The law of conservation of mass states that no atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reactants.
The law of conservation of mass states that no atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reactants.
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Why must we ensure that chemical equations are balanced?
To accurately represent that no atoms are being made or lost during a chemical reaction, they are just converting from one form to another.
This means that chemical reactions can be represented by symbol equations which are balanced in terms of the numbers of atoms of each element involved on both sides of the equation.
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What do the multipliers in normal script before a chemical formula represent? Eg 2MgO
The normal script numbers before a chemical formula represent you have that many of that particular atom or molecule. In the example 2MgO, the 2 represents that there are two molecules of MgO
Students should understand the use of the multipliers in equations in normal script before a formula and in subscript within a formula.
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How do we calculate the relative formula mass (Mr) of a compound?
The relative formula mass (Mr) of a compound is the sum of the relative atomic masses of the atoms in the numbers shown in the formula.
The relative formula mass (Mr) of a compound is the sum of the relative atomic masses of the atoms in the numbers shown in the formula.
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Why must the total relative formula mass of all of the reactants equal that of all of the products made?
The law of conservation of mass states that no atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reactants. Therefore the total atoms before and after a chemical reaction must be the same.
In a balanced chemical equation, the sum of the relative formula masses of the reactants in the quantities shown equals the sum of the relative formula masses of the products in the quantities shown.
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When a gas is produced in a chemical reaction, why would the mass of the products appear to be less than that of the reactants?
The mass of the products will be reduced because the gas escapes into the surroundings. The total number of atoms will not have changed.
Some reactions may appear to involve a change in mass but this can usually be explained because a reactant or product is a gas and its mass has not been taken into account. For example: when a metal reacts with oxygen the mass of the oxide produced is greater than the mass of the metal or in thermal decompositions of metal carbonates carbon dioxide is produced and escapes into the atmosphere leaving the metal oxide as the only solid product.
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Explain why in the reaction below the mass of the products would be greater than that of the reactants 2Mg (s) O2 (g) -> 2MgO (s)
Because oxygen gas would not be accounted for when the mass of the reactants are recorded, yet form part of the solid MgO produced. Therefore giving an increase in mass, but no new atoms were created or destroyed within the reaction.
Students should be able to explain any observed changes in mass in non-enclosed systems during a chemical reaction given the balanced symbol equation for the reaction and explain these changes in terms of the particle model.
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What does the term uncertainty mean?
Whenever a measurement is made there is always some uncertainty about the result obtained.
Whenever a measurement is made there is always some uncertainty about the result obtained.
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How would you represent the distrubtion of results to make estimations of uncertainty?
To represent the distrubution of results and make estimations of uncertainty you should use error bars on a graph.
Students should be able to represent the distribution of results and make estimations of uncertainty
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A pippette has an uncertainty of /-0.01mL. It is used three times in a practical. What is the mean measure of uncertainty?
The uncertainty of a pippette that is used three times is = 3 x 0.01 = /- 0.03mL
Students should be able to use the range of a set of measurements about the mean as a measure of uncertainty.
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(HT only) Chemical amounts are measured in moles. What is the symbol of the unit for moles?
The symbol for the unit mole is mol.
Chemical amounts are measured in moles. The symbol for the unit mole is mol.
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(HT only)How can we calculate the mass of one mole of a substance?
The mass of one mole of a substance is equal to its relative formula mass in grams. Eg. CO2 Mr = 44 : so 1 Mole of CO2 = 44g
How the mass of one mole of a substance calculated.
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(HT only)If you have one mole each of two different substances, what will they share in common?
One mole of a substance contains the same number of the stated particles, atoms, molecules or ions as one mole of any other substance.
One mole of a substance contains the same number of the stated particles, atoms, molecules or ions as one mole of any other substance.
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(HT only)What does Avogadro's constant represent?
The total number of particles/atoms/molecules/ions within one mole of a substance.
The number of atoms, molecules or ions in a mole of a given substance is the Avogadro constant.
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(HT only)What is the value of Avogadro's constant?
1 mole = 6.02 x 1023 particles/atoms/molecules/ions of a substance
The value of the Avogadro constant is 6.02 x 1023 per mole.
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(HT only)Would there be any difference in the number of atoms in one mole of carbon (C) compared with the number of one mole of molecules of carbon dioxide (CO2)?
Measurement of amounts in moles can apply to atoms, molecules, ions, electrons, formulae and equations, for example that in one mole of carbon (C) the number of atoms is the same as the number of molecules in one mole of carbon dioxide (CO2).
Students should understand that the measurement of amounts in moles can apply to atoms, molecules, ions, electrons, formulae and equations, for example that in one mole of carbon (C) the number of atoms is the same as the number of molecules in one mole of carbon dioxide (CO2).
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(HT only)Calculate the mass of one mole of C2H6
The relative formula mass (Mr) of C2H6 = 30 Therefore the mass of 1 mol C2H6 = 30g
Students should be able to use the relative formula mass of a substance to calculate the number of moles in a given mass of that substance and vice versa.
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What units are used for the measurement of concentration of a solution?
The standard measures of concentration of a solution are: grams per dm3 (g/dm3) or moles per dm3 (mol/dm3)
Many chemical reactions take place in solutions. The concentration of a solution can be measured in mass per given volume of solution, eg grams per dm3 (g/dm3).
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What is the concentration of a solution that has 37g of solute dissolved in 100cm3? Give your answer in dm3.
The concentration would be 37g / 100cm3. To convert this to dm3 divide answer by 1000 = 0.0037g/dm3.
Students should be able to calculate the mass of solute in a given volume of solution of known concentration in terms of mass per given volume of solution
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(HT only) What is the equation that relates the mass of a solute, the volume of a solution and the concentration of the solution?
concentration of solution (g/dm3) = mass of a solute (g) / volume of solution (dm3)
Students should be able to (HT only) explain how the mass of a solute and the volume of a solution is related to the concentration of the solution.
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Why industrially is high atom economy important?
It is important for sustainable development and for economic reasons to use reactions with high atom economy.
It is important for sustainable development and for economic reasons to use reactions with high atom economy.
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(HT only)Balance the equation and calculate the mass of the reactants and products of the balanced symbol equation: H2O2 --> H20 02
2H2O2 --> 2H20 02 The mass of the reactants is 68, the mass of the reactants is also 68
The masses of reactants and products can be calculated from balanced symbol equations.
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(HT only)In the following equation: Mg 2HCI --> MgCI2 H2 What is the ratio of magnesium (Mg) atoms react in comparison to that of hydrochloric acid (HCl)?
1:2 This is because chemical equations can be interpreted in terms of moles. Mg + 2HCI --> MgCI2 + H2 The equation shows that one mole of magnesium (Mg) reacts with two moles of hydrochloric acid (HCl)
Chemical equations can be interpreted in terms of moles. For example: Mg + 2HCI --> MgCI2 + H2 shows that one mole of magnesium reacts with two moles of hydrochloric acid to produce one mole of magnesium chloride and one mole of hydrogen gas.
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(HT only)CaCO3 2HCl ---> CaCl2 CO2 H2O Use the above equation to determine the mass of carbon dioxide produced if you react 10g of calcium carbonate with an excess of hydrochloric acid?
4.4g of CO2 is produced
Students should be able to calculate the masses of substances shown in a balanced symbol equation
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(HT only)Calculate the mass of iron produced when 32g of iron (III) oxide is completely reduced by aluminium. The reaction is shown in the symbol equation: Fe2O3 2Al ? 2Fe Al2O3
When 32g of iron (III) oxide is reduced by aluminium 22.4g of iron is produced
Students should be able to calculate the masses of reactants and products from the balanced symbol equation and the mass of a given reactant or product.
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(HT only)How can you use the massess of reactants and products to balance a symbol equation?
The balancing numbers in a symbol equation can be calculated from the masses of reactants and products by converting the masses in grams to amounts in moles and converting the numbers of moles to simple whole number ratios.
The balancing numbers in a symbol equation can be calculated from the masses of reactants and products by converting the masses in grams to amounts in moles and converting the numbers of moles to simple whole number ratios.
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(HT only) Reactants Sb = 488g Cl2 = 426g Products SbCl3= 914g Complete a symbol equation for the reaction above using the masses to balance the equation.
2Sb + 3Cl2 ---> 2SbCl3
Students should be able to balance an equation given the masses of reactants and products.
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(HT only)How do you rearrange the moles equation to find the relative formulat mass? Moles = mass / RFM
The moles equation can be rearranged to find RFM = mass / moles
Students should be able to change the subject of a mathematical equation.
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(HT only)What is meant when a reactant is said to be in excess?
An excess reactant is any reactant in a chemical reaction with a greater amount than necessary to react completely with the all other reactants.
In a chemical reaction involving two reactants, it is common to use an excess of one of the reactants to ensure that all of the other reactant is used.
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What is meant when a reactant is described as a limiting reactant?
A limiting reactant is a reactant that when completely used up the reaction will cease. This is because it limits the amount of products that can be made.
The reactant that is completely used up is called the limiting reactant because it limits the amount of products.
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(HT only) 2H2 O2 --> 2H2O You react 10g of oxygen with 10g of hydrogen. Only 11.25g of product is made the rest of the reactants remain unused. Suggest why the full mass of reactants did not react. What is the leftover unreacted substance?
Oxygen is the limiting reactant in this example. Once all of the oxygen is used up the reaction will be unable to continue. Hydrogen therefore we would describe as being in excess, so the 8.75g of leftover reactant would be unused hydrogen that was not used up during the chemical reaction.
Students should be able to explain the effect of a limiting quantity of a reactant on the amount of products it is possible to obtain in terms of amounts in moles or masses in grams.
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(Chem only) Suggest why it is not always possible obtain the calculated amount of product from a reaction?
You may not always get the maximum yield because the reaction may not go to completion because it is reversible, some of the product may be lost when it is separated from the reaction mixture; or some of the reactants may react in ways different to the expected reaction.
Even though no atoms are gained or lost in a chemical reaction, it is not always possible to obtain the calculated amount of a product because: ??? the reaction may not go to completion because it is reversible ??? some of the product may be lost when it is separated from the reaction mixture; ? some of the reactants may react in ways different to the expected reaction.
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(Chem only) What does the term yield refer to?
The amount of product obtained
The amount of a product obtained is known as the yield.
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(Chem only) What is percentage yield?
When the actual yield obtained is compared with the maximum theoretical yield of a reaction is expressed as a percentage, it is called the percentage yield.
When compared with the maximum theoretical amount as a percentage, it is called the percentage yield. % Yield = Mass of product actually made / Maximum theoretical mass of product ? 100
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(Chem only) What is the formula for calculating percentage yield?
% Yield = Mass of product actually made / Maximum theoretical mass of product ? 100
Students should be able to calculate the percentage yield of a product from the actual yield of a reaction
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(Chem only) What mass of carbon dioxide is formed when 12 g of carbon is burned in air?
1.Write out the equation for the reaction. Make sure it is balanced. C O2 -> CO2 (Carbon is the known, carbon dioxide is the unknown) 2.Work out the relative masses of the substances needed in the calculation. Mass of carbon = 12, mass of carbon dioxide = 44 3.Convert the relative masses into the units in the question. Mass of carbon = 12 g, mass of carbon dioxide is 44 g 4.Find the ratio by dividing both numbers by the smallest number. For carbon 12 ? 12 = 1, for carbon dioxide 44 ? 12 = 3.67 5.Find the mass of the unknown by multiplying the mass of the known by the ratio of the unknown. 3.67 ? 12 = 44 g
(HT only) calculate the theoretical mass of a product from a given mass of reactant and the balanced equation for the reaction.
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(Chem only) What is atom economy a measure of?
The amount of starting materials that end up as useful products.
The atom economy (atom utilisation) is a measure of the amount of starting materials that end up as useful products.
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(Chem only) What is the formula for calculating percentage atom economy?
The percentage atom economy of a reaction is calculated using the balanced equation for the reaction as follows: Relative formula mass of desired product from equation / Sum of relative formula masses of all reactants from equation ? 100
The percentage atom economy of a reaction is calculated using the balanced equation for the reaction as follows: Relative formula mass of desired product from equation / Sum of relative formula masses of all reactants from equation ? 100
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(Chem only) Hydrazine (N2H4) is used in some rocket fuels. Two different methods can be used to manufacture hydrazine. The reactions are: NH2Cl NH3 ? N2H4 HCl 2NH3 H2O2 ? N2H4 2H2O Calculate the atom economy for each reaction
1) Mr of N2H4 = 32 2) Sum of Mr all reactants in equation 1= 68.5 3) (32 / 68.5 ) x100 46.7% 4) Sum of Mr all reactants in equation 2 = 68 5) (32/68) x 100 = 47%
Students should be able to calculate the atom economy of a reaction to form a desired product from the balanced equation
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(Chem only) How can a chemist in a chemical plant that makes rocket fuel prevent waste products being formed?
(HT) A chemist can prevent waste rocket fuel being formed by Choose a reaction with few/no other products.
(HT only) explain why a particular reaction pathway is chosen to produce a specified product given appropriate data such as atom economy (if not calculated), yield, rate, equilibrium position and usefulness of by-products.
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(Chem only) What is mol/dm3 the unit of measurement for?
mol/dm3 is a measure of concentration. It tells us how many moles of that substance you would find in a dm3
The concentration of a solution can be measured in mol/dm3.
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(Chem only) How can we calculate the number of moles of solute in a given volume of a solution?
The amount in moles of solute of solute in a given volume of solution can be calculated from its concentration in mol/dm3 multiplied by the volume of the solution in dm3.
The amount in moles of solute or the mass in grams of solute in a given volume of solution can be calculated from its concentration in mol/dm3.
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(Chem only) What technique can we use if the volumes of two solutions that react completely are known and the concentration of one solution is known, to calculate the concentration of the other solution.
A titration reaction
If the volumes of two solutions that react completely are known and the concentration of one solution is known, the concentration of the other solution can be calculated.
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(Chem only) How can we calculate the mass of a solute within a solution if we know the concentration in mol/dm3?
mass of solute = (concentration (mol dm-3) / relative formula mass) x volume of solution (dm3)
Students should be able to explain how the concentration of a solution in mol/dm3 is related to the mass of the solute and the volume of the solution
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(Chem only) What is the difference between a strong and weak acid?
A strong acid will fully dissociate from all of its H ions whereas a weak acid won't
Opportunities within titrations including to determine concentrations of strong acids and alkalis. (WS)
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(Chem only) Do all gases occupy the same volume?
Equal amounts in moles of gases occupy the same volume under the same conditions of temperature and pressure.
Equal amounts in moles of gases occupy the same volume under the same conditions of temperature and pressure.
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(Chem only) What volume does one mole of any gas occupy at room temperature and pressure?
A single mole of any gas will occupy 24dm3
The volume of one mole of any gas at room temperature and pressure (20oC and 1 atmosphere pressure) is 24 dm3.
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(Chem only) How could you calculate the volume a gas would occupy if you were given the mass of gas made?
1) Calculate the total number of moles of that gas you have (Moles = Mass (g) / Mr) 2) Then calulate the volume that gas would occupy. Volume of gas (dm3) = Moles x 24
The volumes of gaseous reactants and products can be calculated from the balanced equation for the reaction.
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(Chem only) If you have 88g of CO2. What volume would it occupy?
1) Calculate moles first: moles = mass /Mr = 88/44 = 2 2) Calculate the volume of gas made: Volume of gas = Moles x 24 = 2x24 = 48dm3
Students should be able to calculate the volume of a gas at room temperature and pressure from its mass and relative formula mass
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(Chem only) In the reaction CH4 2O2 ? CO2 2H2O (at rtp) what volume of water vapour is produced when 2.4 dm3 of methane burns?
1) Rearrange volume equation for moles to find moles of methane reacting: moles (methane) = volume / 24 moles (methane) = 2.4 / 24 moles (methane) = 0.1 2) Identify molar ratio for reactants and products in question: 1 mole of methane products 2 moles of water, therefore 1:2 ratio 3) Deduce the moles of water using ratio: 0.1 x 2 = 0.2 moles 4) calculate volume of water vapour: volume of gas = moles x 24 volume of gas = 0.2 x 24 = 4.8dm3
Students should be able to calculate volumes of gaseous reactants and products from a balanced equation and a given volume of a gaseous reactant or product
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(Chem only) Rearrange the volume of gas equation to calculate the number of moles
Rearrange volume equation for moles to find moles of methane reacting: moles (methane) = volume / 24
Students should be able to change the subject of a mathematical equation.
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What does the reactivity of a metal depend on?
The reactivity of a metal is related to its tendency to form positive ions.
The reactivity of a metal is related to its tendency to form positive ions.
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How can the reactivity of group 1 metals be compared using a practical investigation?
Group 1 metal reactivity can be compared by observing their reactivity with water and dilute acids qualitatively by looking at the amount of gas produced using a magnifying glass or quantitatively by measuring the temperature changes.
The metals potassium, sodium, lithium, calcium, order of reactivity is from their reactions with water and dilute acids.
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What happens when a metal reacts with oxygen?
Metals react with oxygen to produce metal oxides.
Metals react with oxygen to produce metal oxides.
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What happens to metals in an oxidation reaction?
In oxidation reactions metals gain oxygen and looses electrons.
The reactions are oxidation reactions because the metals gain oxygen.
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What is meant by the term 'reduction'?
Reduction is the loss of oxygen and gain of electrons.
Students should be able to explain reduction and oxidation in terms of loss or gain of oxygen.
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What happens in terms of electrons during reduction and oxidation reactions?
During oxidation reactions substances loose/donate electrons and in reduction reactions substanced gain electrons.
Oxidation is the loss of electrons and reduction is the gain of electrons.
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Why is potassium more reactive than lithium?
Potassium is more reactive than lithium because it can form a postive ion easier. This is because the attraction between the outside electron and the nuclues is far lower in potassium than lithium. This is because potassium is a bigger atom with more electron shells, creating more sheilding of the electrostatic attraction.
Students should be able to explain how the reactivity of metals with water or dilute acids is related to the tendency of the metal to form its positive ion
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What happens during a displacement reaction?
In a displacement reaction a more reactive metal can displace a less reactive metal from a compound.
A more reactive metal can displace a less reactive metal from a compound.
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What would the independent, dependent and control variables be for a quantitative investigation into the reactivity of metals?
To investigate the reactivity of metals quantitatively the independent variable would be the type of metal. The dependent variable would be the temperature increase. The control variables would be the surface area of the metal, the volume and concentration of the water/acid, the temperature of the reactants and the mass of the metal.
Students should be able to deduce an order of reactivity of metals based on experimental results.
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Where in the reactivity series does carbon appear and which elements can be displaced by carbon?
The order of reactivity including non metals is: Pottassium, sodium, lithium, calcium, magnesium, aluminium, carbon, zinc, iron, hydrogen, copper, silver, gold. Only elements below carbon in the reactivity series can be displaced by carbon.
The non-metals hydrogen and carbon are often included in the reactivity series.
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What conditions are standard when investigating the reactivity of metals with water and acids?
The reactions of metals with water and acids are limited to room temperature and do not include reactions with steam.
The reactions of metals with water and acids are limited to room temperature and do not include reactions with steam.
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What is the list of metals (and non-metals) in the reactivity series, from most reactive to least reactive?
Potassium, sodium, lithium, calcium, magnesium, aluminium, carbon, zinc, iron, hydrogen, copper, silver, gold.
Metals can be arranged in order of their reactivity in a reactivity series.
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How do each of the following metals react with each of water and dilute acids: potassium, sodium, lithium, calcium, magnesium, zinc, iron and copper?
Lithium, sodium and potassium have vigorous reactions with cold water and explosive reactions with dilute acids. Calcium, magnesium have less vigorous reactions with water and dilute acids but it is possible to see gas being produced. Zinc, iron and copper have far less vigorous reactions, decreasing in reactivity.
Students should be able to recall and describe the reactions, if any, of potassium, sodium, lithium, calcium, magnesium, zinc, iron and copper with water or dilute acids and where appropriate, to place these metals in order of reactivity
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Write the ionic equation for the displacement reaction between copper ions and magnesium
The equation for the displacement reaction between copper ions and magnesium is: Cu2 Mg --> Mg2 Cu
Student should be able to write ionic equations for displacement reactions
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Why are metals such as gold found in the Earth as the metal itself?
Gold is found in the Earth as the metal itself as it is unreactive.
Unreactive metals such as gold are found in the Earth as the metal itself but most metals are found as compounds that require chemical reactions to extract the metal.
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How can metals less reactive than carbon be extracted from their oxides?
Metals less reactive than carbon can be extracted from their oxides by reduction with carbon.
Metals less reactive than carbon can be extracted from their oxides by reduction with carbon.
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What is meant by 'reduction' in terms of oxygen?
Reduction involves the loss of oxygen.
Reduction involves the loss of oxygen.
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What substance can be used to extract the lesser reactive metals?
Carbon can be used to extract the lesser reactive metals.
Knowledge and understanding are limited to the reduction of oxides using carbon.
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What type of reaction is it when electrons are transferred from one species to another?
When electrons are transferred from one species to another this is called a redox reaction.
Knowledge of the details of processes used in the extraction of metals is not required.
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Identify the species that are oxidised and reduced in the half equations below: Cu2 Mg --> Mg2 Cu
The oxidation half equation is: Mg --> Mg2 2e- The reduction half equation is: Cu2 2e- --> Cu
Students should be able to identify in a given reaction, symbol equation or half equation which species are oxidised and which are reduced.
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What are the products when acids react with metals?
Acids react with some metals to produce salts and hydrogen.
Acids react with some metals to produce salts and hydrogen.
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(HT only) What type of reaction occurs when acids react with metals?
(HT) When acids react with metals there is a transfer of electrons so this is a redox reaction.
(HT only) Students should be able to explain in terms of gain or loss of electrons, that these are redox reactions
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(HT only) In a reaction between copper (II) oxide and carbon, where does each of oxidation and reduction happen?
Carbon is oxidised by gaining oxygen to form carbon dioxide. Copper (in CuO) is reduced by losing oxygen to form copper metal. Copper has changed from Cu2 (in CuO) to Cu(s) and so has gained electrons. Cu2 (aq) 2e-(aq) arrow Cu(s)
Students should be able to identify which species are oxidised and which are reduced in given chemical equations. (HT only)
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When an acid (such as hydrochloric acid) reacts with an alkali or a base (such as sodium hydroxide), what will the two products be?
When an acid reacts with an alkali or base it produces salts and water.
Acids are neutralised by alkalis (eg soluble metal hydroxides) and bases (eg insoluble metal hydroxides and metal oxides) to produce salts and water
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What products are made when an acid reacts with a metal carbonate?
Acids are neutralised by metal carbonates to produce salts, water and carbon dioxide.
Acids are neutralised by metal carbonates to produce salts, water and carbon dioxide.
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What factors affect the type of salt produced in a reaction between an acid and a base or alkali?
The particular salt produced in any reaction between an acid and a base or alkali depends on: - the acid used (hydrochloric acid produces chlorides, nitric acid produces nitrates, sulfuric acid produces sulfates) - the positive ions in the base, alkali or carbonate.
The particular salt produced in any reaction between an acid and a base or alkali depends on: - the acid used (hydrochloric acid produces chlorides, nitric acid produces nitrates, sulfuric acid produces sulfates) - the positive ions in the base, alkali or carbonate.
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What two products would be made when zinc oxide reacts with dilute hydrochloric acid?
The two products that would be made when zinc oxide reacts with dilute hydrochloric acid are zinc chloride and water.
Students should be able to predict products from given reactants
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What examples of solid insoluble substances react with acids to form soluble salts?
Soluble salts can be made from acids by reacting them with solid insoluble substances, such as metals, metal oxides, hydroxides or carbonates.
Soluble salts can be made from acids by reacting them with solid insoluble substances, such as metals, metal oxides, hydroxides or carbonates.
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When an excess of metal oxide reactant is added to an acid, how can the pure salt solution be collected?
The solid is added to the acid until no more reacts and the excess solid is filtered off to produce a solution of the salt.
(WS) The solid is added to the acid until no more reacts and the excess solid is filtered off to produce a solution of the salt.
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What process is used to produce solid soluble salts from salt solutions?
Salt solutions can be crystallised to produce solid salts.
Salt solutions can be crystallised to produce solid salts.
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What are the typical steps are involved in preparing a pure, dry sample of silver chloride from silver nitrate and sodium chloride?
Silver chloride is insoluble - you can see this from the table. You need a soluble silver salt and a soluble chloride salt to make it. Silver nitrate and sodium chloride are both soluble. When you mix their solutions together, you make soluble sodium nitrate and insoluble silver chloride: silver nitrate sodium chloride → sodium nitrate silver chloride AgNO3(aq) NaCl(aq) → NaNO3(aq) AgCl(s) The silver chloride appears as tiny particles suspended in the reaction mixture - it forms a precipitate. The precipitate can be filtered, washed with water on the filter paper, and then dried in an oven.
Students should be able to describe how to make pure, dry samples of named soluble salts from information provided.
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What would the formula be if the following ions reacted to form salts: a) Mg Cl- b) Cu2 S2- c) Fe2 I-
a) MgCl2 b) CuS c) FeI2
Students should be able to use the formulae of common ions to deduce the formulae of salts.
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In what way can universal indicator be used to measure the approximate pH of a solution?
Universal indicator is used to measure the approximate pH of a solution as when it is added to a solution strongly acidic solutions appear red, weakly acidic solutions appear orange/yellow, neutral solutions appear green, weakly alkaline solutions appear blue and strongly alkaline solutions appear purple.
(WS) Students should be able to describe the use of universal indicator or a wide range indicator to measure the approximate pH of a solution
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If a substance has the following pH is it classified as acid, alkali or neutral: 1) pH 3 2) pH 11 3) pH 7
1) pH 3 = acid 2) pH 11 = alkali 3) pH 7 = neutral
(WS) Students should be able to use the pH scale to identify acidic or alkaline solutions.
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What ions are produced in alkalis in aqueous solutions?
Aqueous solutions of alkalis contain hydroxide ions (OH-).
Aqueous solutions of alkalis contain hydroxide ions (OH-).
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What happens to strong acids in an aqueous solution in terms of ionisation?
A strong acid is completely ionised in aqueous solution. Examples of strong acids are hydrochloric, nitric and sulfuric acids.
A strong acid is completely ionised in aqueous solution. Examples of strong acids are hydrochloric, nitric and sulfuric acids.
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What happens to weak acids in an aqueous solution in terms of ionisation?
A weak acid is only partially ionised in aqueous solution. Examples of weak acids are ethanoic, citric and carbonic acids.
A weak acid is only partially ionised in aqueous solution. Examples of weak acids are ethanoic, citric and carbonic acids.
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What ions are produced in acids in aqueous solutions?
Acids produce hydrogen ions (H ) in aqueous solutions.
Acids produce hydrogen ions (H ) in aqueous solutions.
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When an acid is stronger, what effect does this have on the pH?
For a given concentration of aqueous solutions, the stronger an acid, the lower the pH.
For a given concentration of aqueous solutions, the stronger an acid, the lower the pH.
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What happens to the hydrogen ion concentration of a solution when pH decreases by one unit?
As the pH decreases by one unit, the hydrogen ion concentration of the solution increases by a factor of 10.
As the pH decreases by one unit, the hydrogen ion concentration of the solution increases by a factor of 10.
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What is meant by 'dilute' and 'concentrated' (in terms of amount of substance) and 'weak acid' and 'strong acid' (in terms of the degree of ionisation)?
The strength of an acid is a measure of the degree of its ionisation - strong acids are fully ionised but weak acids are only partly ionised. Remember that the opposite of strong is weak. The concentration of an acid is a measure of the number of moles of acid in 1 dm3 of acid solution. For example, 2 mol/dm3 hydrochloric acid is twice as concentrated as 1 mol/dm3 hydrochloric acid or 1 mol/dm3 ethanoic acid. Remember: the opposite of concentrated is dilute.
Students should be able to use and explain the terms dilute and concentrated (in terms of amount of substance), and weak and strong (in terms of the degree of ionisation) in relation to acids
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How is the reaction between hydrogen ions and hydroxide ions to produce water presented as an equation?
This reaction can be represented by the equation: H (aq) OH-(aq) -> H2O(l)
This reaction can be represented by the equation: H (aq) OH-(aq) -> H2O(l)
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How is water produced in a neutralisation reaction between an acid and an alkali in terms of ions?
In neutralisation reactions between an acid and an alkali, hydrogen ions react with hydroxide ions to produce water.
In neutralisation reactions between an acid and an alkali, hydrogen ions react with hydroxide ions to produce water.
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What piece of digital equipment can be used to measure the pH of a solution?
A digital pH probe can be used to measure the acidity or alkalinity of a solution more accurately and precisely than universal indicator.
The pH scale, from 0 to 14, is a measure of the acidity or alkalinity of a solution, and can be measured using universal indicator or a pH probe.
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What pH values do each of acidic, alkaline and neutral solutions have?
A solution with pH 7 is neutral. Aqueous solutions of acids have pH values of less than 7 and aqueous solutions of alkalis have pH values greater than 7.
A solution with pH 7 is neutral. Aqueous solutions of acids have pH values of less than 7 and aqueous solutions of alkalis have pH values greater than 7.
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A sample of vinegar contains 0.1 mol/dm3 ethanoic acid. What is its concentration in g/dm3? (The relative formula mass, Mr, of ethanoic acid is 60)
concentration in g/dm3 = concentration in g/dm3 ? Mr concentration = 0.1 ? 60 = 6 g/dm3 Answer 6 g/dm3
(MS) (HT Only) calculate the chemical quantities in titrations involving concentrations in mol/dm3 and in g/dm3.
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25 cm3 of dilute hydrochloric acid is neutralised by 20 cm3 of 0.5 mol/dm3 sodium hydroxide. What is the concentration of the hydrochloric acid?
Step 1: Convert volumes to dm3 25 cm3 of HCl = 25 /1000 = 0.025 dm3 20 cm3 of NaOH = 20 / 1000 = 0.020 dm3 Step 2: Determine the number of moles of sodium hydroxide moles of NaOH = concentration ? volume moles of NaOH = 0.5 x 0.020 = 0.010 mol Step 3: Work out the number of moles of acid using the balanced equation HCl(aq) NaOH(aq) ? NaCl(aq) H2O(l) In this reaction, one mole of HCl reacts with one mole of NaOH. This is a 1:1 ratio. Therefore, in our titration, 0.010 mol of NaOH must neutralise 0.010 mol of HCl. Step 4: Calculate the concentration of the acid concentration of HCl = number of moles / volume concentration of HCl = 0.010 / 0.025 = 0.4 mol/dm3 Answer The concentration of the HCl is 0.4 mol/dm3.
(MS) (HT only) determination of the concentration of one of the solutions in mol/dm3 and g/dm3 from the reacting volumes and the known concentration of the other solution.
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How can the volumes of acid and alkali solutions that react with each other be measured?
The volumes of acid and alkali solutions that react with each other can be measured by titration using a suitable indicator.
The volumes of acid and alkali solutions that react with each other can be measured by titration using a suitable indicator.
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What does conservation of energy mean?
Energy is conserved in chemical reactions. The amount of energy in the universe at the end of a chemical reaction is the same as before the reaction
Energy is conserved in chemical reactions. The amount of energy in the universe at the end of a chemical reaction is the same as before the reaction takes place.
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In what circumstance is energy transferred to the surroundings during a chemical reaction?
If a reaction transfers energy to the surroundings the product molecules must have less energy than the reactants, by the amount transferred.
If a reaction transfers energy to the surroundings the product molecules must have less energy than the reactants, by the amount transferred.
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What happens to the energy in an exothermic reaction?
An exothermic reaction is one that transfers energy to the surroundings so the temperature of the surroundings increases.
An exothermic reaction is one that transfers energy to the surroundings so the temperature of the surroundings increases.
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What are three examples of exothermic reactions?
Exothermic reactions include combustion, many oxidation reactions and neutralisation.
Exothermic reactions include combustion, many oxidation reactions and neutralisation.
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What is an example of an exothermic reaction in everyday life?
Everyday uses of exothermic reactions include self-heating cans and hand warmers.
Everyday uses of exothermic reactions include self-heating cans and hand warmers.
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What happens to the energy in an endothermic reaction?
An endothermic reaction is one that takes in energy from the surroundings so the temperature of the surroundings decreases.
An endothermic reaction is one that takes in energy from the surroundings so the temperature of the surroundings decreases.
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What are three examples of endothermic reactions?
Endothermic reactions include thermal decompositions and the reaction of citric acid and sodium hydrogencarbonate
Endothermic reactions include thermal decompositions and the reaction of citric acid and sodium hydrogencarbonate. Some sports injury packs are based on endothermic reactions.
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What is an example of an endothermic reaction in everyday life?
Everyday uses of endothermic reactions are some sports injury (ice) packs.
Some sports injury packs are based on endothermic reactions.
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When a chemical reaction occurs and the temperature of the surroundings has increased, is it an exothermic or endothermic reaction?
When a chemical reaction occurs and the temperature of the surroundings has increased the chemical reaction is exothermic.
Students should be able to distinguish between exothermic and endothermic reactions on the basis of the temperature change of the surroundings
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What are the advantages of using exothermic reactions for hand warmers?
The advantages of using exothermic reactions for hand warmers is that they keep your hands warm because they release thermal energy to the surroundings.
Students should be able to evaluate uses and applications of exothermic and endothermic reactions given appropriate information.
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What is the temperature change of the solution if the starting temperature was 20 degrees and the end temperature was -5 degrees. State if this is endothermic or exothermic.
The energy change would be (-)15 degrees. This is an endothermic reaction.
Limited to measurement of temperature change. Calculation of energy changes or ?H is not required.
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Why do some collisions between reactant particles not result in a product forming?
Chemical reactions can occur only when reacting particles collide with each other and with sufficient energy. This doesn't always happen.
Chemical reactions can occur only when reacting particles collide with each other and with sufficient energy.
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What does the term activation energy mean?
The minimum amount of energy that particles must have to react is called the activation energy.
The minimum amount of energy that particles must have to react is called the activation energy.
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What information can be shown in a reaction profile?
Reaction profiles can be used to show the relative energies of reactants and products, the activation energy and the overall energy change of a reaction.
Reaction profiles can be used to show the relative energies of reactants and products, the activation energy and the overall energy change of a reaction.
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What would the simple reaction profile for an exothermic reaction look like?
For an exothermic reaction the reaction profile would show the energy level for the reactants to be lower than the energy level for the products. A curved line is used to show the activation energy required for the reaction (this is higher than the products energy level)
Students should be able to draw simple reaction profiles (energy level diagrams) for exothermic and endothermic reactions showing the relative energies of reactants and products, the activation energy and the overall energy change, with a curved line to show the energy as the reaction proceeds
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What would the simple reaction profile for an endothermic reaction look like?
For an endothermic reaction the reaction profile would show the energy level for the reactants to be higher than the energy level for the products. A curved line is used to show the activation energy required for the reaction (this is higher than the reactants energy level)
Students should be able to use reaction profiles to identify reactions as exothermic or endothermic
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What information does the activation energy provide?
The activation energy is the energy needed for a reaction to occur.
Students should be able to explain that the activation energy is the energy needed for a reaction to occur.
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What energy transfers occur during breaking bonds of reactants and forming new bonds of products?
During a chemical reaction energy must be supplied to break bonds in the reactants and energy is released when bonds in the products are formed.
During a chemical reaction energy must be supplied to break bonds in the reactants and energy is released when bonds in the products are formed.
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What information can bond energies provide?
Bond energies tell us the energy needed to break bonds and the energy released when bonds are formed.
The energy needed to break bonds and the energy released when bonds are formed can be calculated from bond energies.
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How is the overall energy change of a reaction calculated?
The overall energy change is calculated by working out the difference between the sum of the energy needed to break bonds in the reactants and the sum of the energy released when bonds in the products are formed is the overall energy change of the reaction.
The difference between the sum of the energy needed to break bonds in the reactants and the sum of the energy released when bonds in the products are formed is the overall energy change of the reaction.
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What happens in an exothermic reaction in terms of energy, bond making and bond breaking?
In an exothermic reaction, the energy released from forming new bonds is greater than the energy needed to break existing bonds.
In an exothermic reaction, the energy released from forming new bonds is greater than the energy needed to break existing bonds.
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What happens in an endothermic reaction in terms of energy, bond making and bond breaking?
In an endothermic reaction, the energy needed to break existing bonds is greater than the energy released from forming new bonds.
In an endothermic reaction, the energy needed to break existing bonds is greater than the energy released from forming new bonds.
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What is the energy transferred in the following chemical reaction: hydrogen bromide decomposing to form hydrogen and bromine? 2 ? (H?Br) ? H?H Br?Br The bond energies relevant to this reaction are shown below: H?Br 366 kJ/mol H?H 436 kJ/mol Br?Br 193kJ/mol
1.Energy in = 2 ? 366 = 732 kJ/mole 2.Energy out = 436 + 193 = 629 kJ/mole 3.Energy change = in ? out = 732 ? 629 = +103 kJ/mole The energy change is positive, showing that energy is taken in from the surroundings in an endothermic reaction.
Students should be able to calculate the energy transferred in chemical reactions using bond energies supplied.
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How can the amount of energy transferred during a chemical reaction be measured using a practical?
A calorimeter can be used to measure the energy change of a reaction. Equipment needed: polystyrene cup, lid, thermometer, measuring cylinder, spatula. Add 10mL of solution to the beaker and record the starting temperature. Add one spatula of the powder of the reactants. Record the change in temperature. Subtract the end temperature from the start temperature.
Required practical 4 - temperature change in reactions (AT skills 1,3,5,6)
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Why are chemical cells useful?
Cells contain chemicals which react to produce electricity.
Cells contain chemicals which react to produce electricity.
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What factors can affect the voltage produced by a chemical cell?
The voltage produced by a cell is dependent upon a number of factors including the type of electrode and electrolyte.
The voltage produced by a cell is dependent upon a number of factors including the type of electrode and electrolyte.
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How can a simple chemical cell be made?
A simple cell can be made by connecting two different metals in contact with an electrolyte.
A simple cell can be made by connecting two different metals in contact with an electrolyte.
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What is the structure of a battery like?
Batteries consist of two or more cells connected together in series to provide a greater voltage
Batteries consist of two or more cells connected together in series to provide a greater voltage.
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Why do re-chargeable cells and batteries stop working?
In non-rechargeable cells and batteries the chemical reactions stop when one of the reactants has been used up.
In non-rechargeable cells and batteries the chemical reactions stop when one of the reactants has been used up. Alkaline batteries are non-rechargeable.
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How can re-chargeable cells and batteries be re-charged?
Rechargeable cells and batteries can be recharged because the chemical reactions are reversed when an external electrical current is supplied.
Rechargeable cells and batteries can be recharged because the chemical reactions are reversed when an external electrical current is supplied.
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Which cell would be the best choice to use to power a machine? Cell A produces 0.01V of energy and cell B produces 0.20V of energy. Give a reason for your answer.
Cell B would be the better choice to power a machine as it produces more electricity.
Students should be able to interpret data for relative reactivity of different metals and evaluate the use of cells.
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What type of batteries are non-rechargeable?
Alkaline batteries are non-rechargable.
Students do not need to know details of cells and batteries other than those specified.
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How do fuel cells produce a potential difference?
Fuel cells are supplied by an external source of fuel (eg hydrogen) and oxygen or air. The fuel is oxidised electrochemically within the fuel cell to produce a potential difference.
Fuel cells are supplied by an external source of fuel (eg hydrogen) and oxygen or air. The fuel is oxidised electrochemically within the fuel cell to produce a potential difference.
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What sort of reaction occurs in a hydrogen fuel cell?
The overall reaction in a hydrogen fuel cell involves the oxidation of hydrogen to produce water.
The overall reaction in a hydrogen fuel cell involves the oxidation of hydrogen to produce water.
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What do hydrogen fuel cells offer alternatives to?
Hydrogen fuel cells offer a potential alternative to rechargeable cells and batteries.
Hydrogen fuel cells offer a potential alternative to rechargeable cells and batteries.
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What are the advantages and disadvantages of using hydrogen fuel cells compared with rechargeable cells and batteries?
Similarities: Both convert chemical energy directly into electrical energy using ?spontaneous? redox reactions / Both function in similar ways ? that is, there is a negative electrode where an oxidation half-reaction occurs and a positive electrode where a reduction half-reaction occurs / Both generate electrical energy using chemical energy (compounds in the cells undergo chemical reactions which send electrons into an external circuit) / Both generate a current through an external circuit, which is caused by the separation of the half-reactions part of a full redox reaction / Both are made up of an electrolyte, an anode, and a cathode. Differences: The hydrogen oxygen fuel cell is an energy conversion device while the rechargeable battery is an energy storage device / Fuel cells can only provide electrical energy when reactants (fuel) are constantly provided to the cell (open system) / Rechargeable batteries have chemical energy stored in its parts, in a closed system, and so can provide electricity until its stored chemical energy is used up, at which point the battery requires recharging to renew its chemical energy level. Fuel cells do not require charging, as long as reactants continue to be provided, whereas rechargeable batteries must be charged, which takes the battery out of operation for a period of time / Fuel cells can provide electrical energy for a much longer duration, whereas rechargeable batteries can only provide energy in an intermittent schedule / Electrodes in fuel cells are made of porous material, which allows for the free movement of hydrogen, oxygen, and water, while those in rechargeable batteries are made of solid metal compounds and lattices / Currently, fuel cells are much more expensive than rechargeable batteries, due to the high prices of its individual parts, such as the platinum catalysts / Currently, fuel cells are far larger than rechargeable batteries / Fuel cells are able to generate a large amount of electrical energy, much greater than that produced by rechargeable batteries.
Students should be able to evaluate the use of hydrogen fuel cells in comparison with rechargeable cells and batteries
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(HT only) What are the half equations for the electrode reactions in a hydrogen fuel cell?
(HT only) At the cathode (negative electrode): H2(g) – 2e– → 2H (aq) At the anode (positive electrode): 4H (aq) O2(g) 4e– → 2H2O(g)
Students should be able to write the half equations for the electrode reactions in the hydrogen fuel cell. (HT only)
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When is an ionic compound able to conduct electricity?
When an ionic compound is melted or dissolved in water, the ions are free to move about within the liquid or solution. These liquids and solutions are able to conduct electricity and are called electrolytes.
When an ionic compound is melted or dissolved in water, the ions are free to move about within the liquid or solution. These liquids and solutions are able to conduct electricity and are called electrolytes.
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(HT) What is the balanced half equation for H ? e??? H2
T(HT)he balanced half equation is: 2H ? 2e??? H2
(HT only) Write balanced half equations and ionic equations where appropriate.
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What happens at each of the electrodes in electrolysis when an electric current is passed through the electroytes?
Passing an electric current through electrolytes causes the ions to move to the electrodes. Positively charged ions move to the negative electrode (the cathode), and negatively charged ions move to the positive electrode (the anode). Ions are discharged at the electrodes producing elements. This process is called electrolysis.
Passing an electric current through electrolytes causes the ions to move to the electrodes. Positively charged ions move to the negative electrode (the cathode), and negatively charged ions move to the positive electrode (the anode). Ions are discharged at the electrodes producing elements. This process is called electrolysis.
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(HT) What happens at the anode and cathode electrodes in the electrolysis of aqueous sodium chloride? (use half equations to help explain)
(HT) At the cathode sodium is formed: 2Na 2e- --> 2Na At the anode chlorine gas is formed: 2Cl- -->Cl2 2e-
(HT only) Throughout Section 4.4.3 Higher Tier students should be able to write half equations for the reactions occurring at the electrodes during electrolysis, and may be required to complete and balance supplied half equations. (MS)
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Which electrode as the metals and non metals products found during electrolysis?
During electrolysis the metal product is found at the cathode as this cathode is negatively charged. The non metal product is found at the anode, this this electrode is positively charged.
When a simple ionic compound (eg lead bromide) is electrolysed in the molten state using inert electrodes, the metal (lead) is produced at the cathode and the non-metal (bromine) is produced at the anode.
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What would the products be for the electrolysis of the following ionic compounds: 1. NaCl 2. PbBr2 3. NaOH 4. Al2O3
The products of electrolysis would be: 1. H2 (g) Cl2 (g) NaOH (aq) 2. Pb (s) Br2 (g) 3. H2 (g) O2 (g) Na (aq) 4. Al (s) O2 (g)
Students should be able to predict the products of the electrolysis of binary ionic compounds in the molten state.
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(HT) What would the half equations be for the electrolysis of NaCl?
(HT) anode: 2Cl– → Cl2 2e- (oxidation) cathode: 2H 2e– → H2 (reduction). NaOH solution is also produced.
(HT only) students should be able to write half equations for the reactions occurring at the electrodes during electrolysis, and may be required to complete and balance supplied half equations for this process . (MS)
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What happens at the cathode during electrolysis? Is this an oxidation or reduction reaction?
During electrolysis, at the cathode (negative electrode), positively charged ions gain electrons and so the reactions are reductions.
During electrolysis, at the cathode (negative electrode), positively charged ions gain electrons and so the reactions are reductions.
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What happens at the anode during electrolysis? Is this an oxidation or reduction reaction?
At the anode (positive electrode), negatively charged ions lose electrons and so the reactions are oxidation reactions.
At the anode (positive electrode), negatively charged ions lose electrons and so the reactions are oxidation reactions.
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What would the half equations be during the electrolysis of PbBr2?
anode: 2Br– → Br2 2e- (oxidation) cathode: Pb2 2e– → Pb (reduction).
Reactions at electrodes can be represented by half equations, for example: 2H 2e- ? H2 and 4OH- ? O2 2H2O 4e- or 4OH- 4e- ? O 2H2O
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When is electrolysis used to extract metals from their ores?
Metals can be extracted from molten compounds using electrolysis. Electrolysis is used if the metal is too reactive to be extracted by reduction with carbon or if the metal reacts with carbon.
Metals can be extracted from molten compounds using electrolysis. Electrolysis is used if the metal is too reactive to be extracted by reduction with carbon or if the metal reacts with carbon.
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What is the main drawback of using electrolysis to extract metals?
The main drawback of using electrolysis to extract metals is that a large amount of energy is used to melt the compounds and to produce the electrical current.
Large amounts of energy are used in the extraction process to melt the compounds and to produce the electrical current.
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How is aluminium extracted from its metal ore (aluminium oxide)?
Aluminium is manufactured by the electrolysis of a molten mixture of aluminium oxide and cryolite using carbon as the positive electrode (anode).
Aluminium is manufactured by the electrolysis of a molten mixture of aluminium oxide and cryolite using carbon as the positive electrode (anode).
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Why is a mixture used as the electrolyte in electrolysis?
A mixture is used as the electrolyte in electrolysis as the atoms are not chemically bonded they can be separated.
Students should be able to explain why a mixture is used as the electrolyte
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Why does the positive electrode (the anode) need to be replaced regularly?
Oxygen forms at the positive electrodes (anodes). This oxygen reacts with the carbon of the positive electrodes, forming carbon dioxide, and they gradually burn away.
Students should be able to explain why the positive electrode must be continually replaced.
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(HT)What are the missing reactants and products of the half equation shown below: Mg2 ___--> _____
(HT) Mg2 2e- --> Mg
(HT only) students should be able to write half equations for the reactions occurring at the electrodes during electrolysis, and may be required to complete and balance supplied half equations for this process . (MS)
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Why is hydrogen produced instead of sodium in the electrolysis of NaCl solution?
The ions discharged when an aqueous solution is electrolysed using inert electrodes depend on the relative reactivity of the elements involved. Sodium is more reactive than hydrogen so forms NaOH in solution. Hydrogen gas is discharged at the electrode.
The ions discharged when an aqueous solution is electrolysed using inert electrodes depend on the relative reactivity of the elements involved.
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When is hydrogen produced at the negative electrode in electrolysis?
At the negative electrode (cathode), hydrogen is produced if the metal is more reactive than hydrogen.
At the negative electrode (cathode), hydrogen is produced if the metal is more reactive than hydrogen.
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When is oxygen not produced at the positive electrode?
At the positive electrode (anode), oxygen is produced unless the solution contains halide ions when the halogen is produced.
At the positive electrode (anode), oxygen is produced unless the solution contains halide ions when the halogen is produced.
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Why are hydrogen and oxygen often discharged in the electrolysis of aqueous ionic solutions?
Oxygen and hydrogen gas are discharged because in the aqueous solution water molecules break down producing hydrogen ions and hydroxide ions that are discharged.
This happens because in the aqueous solution water molecules break down producing hydrogen ions and hydroxide ions that are discharged.
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What are the three products made in the electrolysis of aqueous sodium chloride?
The three products of the electrolysis of NaCl would be NaOH, Cl2 and H2.
Students should be able to predict the products of the electrolysis of aqueous solutions containing a single ionic compound.
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(HT)
(HT)
(HT only) students should be able to write half equations for the reactions occurring at the electrodes during electrolysis, and may be required to complete and balance supplied half equations for this process . (MS)
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How can you separate a solution of copper II sulfate to extract low grade copper ores? (include equipment)
Electrolysis can be used to extract low grade copper ores. Equipment needed: DC power supply, wires, graphite electrodes, beaker, copper sulfate solution. Connect the graphite electrodes to the power supply, immerse into the solution and switch on. Wait. copper ions will be collected at cathode and oxygen gas will be collected at the anode.
Required practical 3 - electrolysis (developing hypothesis) (AT skills 3,7,8)
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How can the rate of a chemical reaction be calculated?
The rate of a chemical reaction can be found by measuring the quantity of a reactant used or the quantity of product formed over time: mean rate of reaction = quantity of reactant used / time taken OR mean rate of reaction = quantity of product formed / time taken
The rate of a chemical reaction can be found by measuring the quantity of a reactant used or the quantity of product formed over time: mean rate of reaction = quantity of reactant used / time taken OR mean rate of reaction = quantity of product formed / time taken
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How is the quantity of a reactant or product measured?
The quantity of reactant or product can be measured by the mass in grams or by a volume in cm3.
The quantity of reactant or product can be measured by the mass in grams or by a volume in cm3.
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What are the units for rate of reaction?
The units of rate of reaction may be given as g/s or cm3/s.
The units of rate of reaction may be given as g/s or cm3/s.
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(HT only) What is the third unit that is used to measure the rate of reaction in terms of moles?
(HT only) The quantity of reactants in terms of moles and units for rate of reaction in mol/s.
Students are also required to use quantity of reactants in terms of moles and units for rate of reaction in mol/s. (HT only)
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What would the total amount of a product formed if the rate of reaction is 4g/s and the reaction continues for 3 minutes?
The total amount of product formed if the rate of reaction is 4g/s and the reaction continues for 3 minutes would be 540g. This is worked out by: 3 x 60 = 180s 4g x 180s = 540g
Students should be able to calculate the mean rate of a reaction from given information about the quantity of a reactant used or the quantity of a product formed and the time taken
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What key features must be included for graphs showing the quantity of product formed or quantity of reactant used up against time?
The key features of a graph to show the quantity of product formed or reactant used up would be an appropriate scale, labels with units and a line of best fit excluding anomalies.
Students should be able to draw, and interpret, graphs showing the quantity of product formed or quantity of reactant used up against time
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How do you draw a tangent on a curve to measure the rate of a reaction on a graph?
To draw a tangent on a curve to measure the rate of reaction you should find a straight part of the curve of best fit. The slope of the tangent can be used to measure the rate reaction. The steeper the tangent the faster the rate of the reaction.
Students should be able to draw tangents to the curves on these graphs and use the slope of the tangent as a measure of the rate of reaction
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(HT only) How do you calculate the gradient of a tangent of a curve from a graph?
(HT only) To calculate the gradient of a tangent: 1. choose any two points on the line. 2. draw a right-angled triangle with the line as hypotenuse. 3. use the scale on each axis to find the triangle's: vertical length. horizontal length. 4. work out the vertical length ÷ horizontal length. 5. the result is the gradient of the line
Students should be able to (HT only) calculate the gradient of a tangent to the curve on these graphs as a measure of rate of reaction at a specific time.
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What are the main principals of the collision theory?
Collision theory explains how various factors affect rates of reactions. According to this theory, chemical reactions can occur only when reacting particles collide with each other and with sufficient energy.
Collision theory explains how various factors affect rates of reactions. According to this theory, chemical reactions can occur only when reacting particles collide with each other and with sufficient energy.
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What factors can affect the rate of a chemical reaction?
Factors which affect the rates of chemical reactions include: the concentrations of reactants in solution, the pressure of reacting gases, the surface area of solid reactants, the temperature and the presence of catalysts.
Factors which affect the rates of chemical reactions include: the concentrations of reactants in solution, the pressure of reacting gases, the surface area of solid reactants, the temperature and the presence of catalysts.
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What does the term activation energy mean?
The minimum amount of energy that particles must have to react is called the activation energy.
The minimum amount of energy that particles must have to react is called the activation energy.
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How does increasing the temperature increase the rate of a chemical reaction?
Increasing the temperature increases the frequency of collisions and makes the collisions more energetic, and so increases the rate of reaction.
The minimum amount of energy that particles must have to react is called the activation energy.
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How does increasing the pressure of reacting gases affect the rate of a chemical reaction?
Increasing the pressure of reactant gases increases the rate of chemical reactions.
Students should be able to recall how changing the pressure of reacting gases affects the rate of chemical reactions.
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How does decreasing the temperature of a chemical reaction affect the rate?
Decreasing the temperature of a chemical reaction decreases the rate of the reaction.
Students should be able to recall how changing the temperature affects the rate of chemical reactions.
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How does increasing the surface area to volume ration of a solid reactant affect the rate of a chemical reaction?
Increasing the surface area to volume ratio will increase the rate of the chemical reaction because the there will be more contact between the reactant particles. Increasing the frequency of successful collisions.
Students should be able to predict and explain the effects of changes in the size of pieces of a reacting solid in terms of surface area to volume ratio
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How does increasing the concentration of reactants in reacting gases, and the surface solution, the pressure of area of solid reactants increase the rate of a chemical reaction?
Increasing the concentration of reactants in solution, the pressure of reacting gases, and the surface area of solid reactants increases the frequency of collisions and so increases the rate of reaction.
Increasing the concentration increases the frequency of collisions and makes the collisions and so increases the rate of reaction.
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How does increasing the concentration of reactants in solution affect the rate of chemical reactions?
Increasing the concentration of reactants in solution increases the rate of chemical reactions.
Students should be able to recall how changing the concentrations of reactants in solution affects the rate of chemical reactions.
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How does changing the concentration of a reactant from 1M to 2M affect the rate of a chemical reaction?
When the reactant concentration is 2M there are twice as many particles to react. This means the time it would take for the same number of successful collisions will half.
Students should be able to use simple ideas about proportionality when using collision theory to explain the effect of a factor on the rate of a reaction.
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How does increasing the concentration of a solution reactant or the pressure of a gas reactant affect the rate of a chemical reaction?
Increasing the concentration of a solution reactant or the pressure of a gas reactant will increase the rate of a chemical reaction because there would a higher number of particles in the same area, therefore successful collisions between reactants particles will be more frequent, increasing the rate of reaction.
Students should be able to predict and explain using collision theory the effects of changing conditions of concentration, pressure and temperature on the rate of a reaction
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How does increasing the surface area of solid reactants affect the rate of a chemical reaction?
Increasing the surface area of solid reactants will increase the rate of a chemical reaction.
Students should be able to recall how changing the surface area of solid reactants affects the rate of chemical reactions.
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What are the key characteristics of a catalyst?
Catalysts change the rate of chemical reactions but are not used up during the reaction. Different reactions need different catalysts.
Catalysts change the rate of chemical reactions but are not used up during the reaction. Different reactions need different catalysts.
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What is an example of a biological catalyst?
Enzymes act as catalysts in biological systems.
Enzymes act as catalysts in biological systems.
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How do catalysts increase the rate of chemical reactions?
Catalysts increase the rate of reaction by providing a different pathway for the reaction that has a lower activation energy.
Catalysts increase the rate of reaction by providing a different pathway for the reaction that has a lower activation energy. * An opportunity to investigate the catalytic effect of adding different metal salts to a reaction such as the decomposition of hydrogen peroxide.
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What would the reaction profile for a reaction in the presence of a catalyst look like compared to the same reaction without a catalyst?
The reaction profile for a catalyst would be lower than the pathway for the uncatalysed reaction. The catalyst reaction would be labelled Ea.
A reaction profile for a catalysed reaction can be drawn in the following form: (energy level diagram with reduced Ea with catalyst)
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Are catalysts included in the equation for a chemical reaction? Give a reason for your answer.
Catalysts are not included in the chemical equation for a reaction. This is because they are not used up in the chemical reaction.
Students should be able to identify catalysts in reactions from their effect on the rate of reaction and because they are not included in the chemical equation for the reaction.
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What is the relationship between catalytic action and activation energy?
The relationship between catalytic action and activation energy is that the more effective the catalyst, the lower the activation energy is.
Students should be able to explain catalytic action in terms of activation energy.
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What is the name of the catalyst used in the extraction of aluminium oxide?
The catalyst used in the extraction of aluminium oxide is cryolite.
Students do not need to know the names of catalysts other than those specified in the subject content.
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How does the presence of a catalyst affect the rate of a chemical reaction?
The presence of a catalyst increases the rate of a chemical reaction.
Students should be able to recall how the presence of a catalyst affects the rate of chemical reactions.
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What equipment would you need to investigate the rate of a chemical reaction?
Equipment you would need to investigate the rate of a chemical reaction: timer / stop watch measuring cylinder reactants balance gas syringe if product is a gas balance conical flask
Required practical 5 - rates of reaction (developing a hypothesis) (AT skills 1,3,5,6)
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What is a reversible reaction?
A reversible reaction is one where the products of the reaction can react to produce the original reactants.
In some chemical reactions, the products of the reaction can react to produce the original reactants.
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How can reversible reactions be represented?
Reversible reactions can be represented by: A B (reversible arrow) C D
Such reactions are called reversible reactions and are represented: A B (reversible arrow) C D
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If the reversible reaction below was heated which direction would it react? Ammonium chloride (reversible arrow) ammonia hydrogen chloride
If the reversible reaction of ammonium chloride was heated it would decompose to produce ammonia and hydrogen chloride.
For example: ammonium chloride (heat - reversible arrow - cool) ammonia hydrogen chloride.
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If a reversible reaction is exothermic in one direction, what is it in the opposite direction?
If a reversible reaction is exothermic in one direction, it is endothermic in the opposite direction.
If a reversible reaction is exothermic in one direction, it is endothermic in the opposite direction.
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If 3500 KJ of energy is transferred in the forward reaction, how much energy would be transferred in the reverse reaction?
In a reversible reaction the same amount of energy is transferred in each case so 3500 KJ would be transferred in the reverse reaction.
In a reversible reaction the same amount of energy is transferred in each case. For example: hydrated copper sulfate [blue] (endothermic - reversible arrow - exothermic) anhydrous copper sulfate [white] water.
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How can the direction of reversible reactions be changed?
The direction of reversible reactions can be changed by changing the conditions such as temperature and pressure of gases.
The direction of reversible reactions can be changed by changing the conditions.
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What would happen if the temperature was increased for the reaction below: N2(g) 3H2(g) (reversible reaction) 2NH3(g) The forward reaction is exothermic.
If the temperature is increased, then the equilibrium will shift to the left (the endothermic direction), to remove the extra heat added. This is why only a moderately high temperature (380 - 450°C) is used in the Haber process.
If the temperature of a system at equilibrium is increased: - the relative amount of products at equilibrium increases for an endothermic reaction - the relative amount of products at equilibrium decreases for an exothermic reaction.
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What would happen if the temperature was decreased for the reaction below: N2(g) 3H2(g) (reversible reaction) 2NH3(g) The forward reaction is exothermic.
If the temperature is decreased, then the equilibrium will shift to the right (the exothermic direction), to produce additional heat.
If the temperature of a system at equilibrium is decreased: - the relative amount of products at equilibrium decreases for an endothermic reaction - the relative amount of products at equilibrium increases for an exothermic reaction.
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Does increasing the temperature of a reaction favor the endothermic or exothermic reaction?
Increasing the temperature always favours the endothermic reaction. Decreasing the temperature always favours the exothermic reaction
Students should be able to interpret appropriate given data to predict the effect of a change in temperature on given reactions at equilibrium.
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What does the term equilibrium mean?
When a reversible reaction occurs in apparatus which prevents the escape of reactants and products, equilibrium is reached when the forward and reverse reactions occur at exactly the same rate.
When a reversible reaction occurs in apparatus which prevents the escape of reactants and products, equilibrium is reached when the forward and reverse reactions occur at exactly the same rate.
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How does increasing and decreasing the pressure for gaseous reactions at equilibrium?
For gaseous reactions at equilibrium: - an increase in pressure causes the equilibrium position to shift towards the side with the smaller number of molecules as shown by the symbol equation for that reaction - a decrease in pressure causes the equilibrium position to shift towards the side with the larger number of molecules as shown by the symbol equation for that reaction.
For gaseous reactions at equilibrium: ? an increase in pressure causes the equilibrium position to shift towards the side with the smaller number of molecules as shown by the symbol equation for that reaction ? a decrease in pressure causes the equilibrium position to shift towards the side with the larger number of molecules as shown by the symbol equation for that reaction.
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When does changing the pressure of gaseous reactions not affect the equilibrium?
Changes in pressure will not affect the position of equilibrium, if the number of moles of gases on both sides of the equation are equal. Remember, liquids and solids contribute nothing to the volume of the equilibrium mixture.
Students should be able to interpret appropriate given data to predict the effect of pressure changes on given reactions at equilibrium.
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What does the relative amounts of all the reactants and products at equilibrium depend on?
The relative amounts of all the reactants and products at equilibrium depend on the conditions of the reaction.
The relative amounts of all the reactants and products at equilibrium depend on the conditions of the reaction.
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What happens when a system is at equilibrium and a change is made to the conditions?
If a system is at equilibrium and a change is made to any of the conditions, then the system responds to counteract the change.
If a system is at equilibrium and a change is made to any of the conditions, then the system responds to counteract the change.
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What is Le Chatelier's principle used for?
The effects of changing conditions on a system at equilibrium can be predicted using Le Chatelier's Principle.
The effects of changing conditions on a system at equilibrium can be predicted using Le Chatelier's Principle.
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How would changing the conditions of the equation below effect the equilibrium? A(g) 2B (g) (reversible arrow) C(g) D(g) a) increasing concentration of A b) increasing the pressure of the reactants c) increasing the temperature of the reaction (the forward reaction is exothermic)
Changing the conditions of the equation below would have the following effects on the equilibrium: A(g) 2B (g) (reversible arrow) C(g) D(g) a) equilibrium would shift to the right to reduce the amount of A particles b) equilibrium would shift to the right as there are fewer gas molecules in the products than in the reactants c) equilibrium would shift to the left as the reaction tries to cool itself down again
Students should be able to make qualitative predictions about the effect of changes on systems at equilibrium when given appropriate information.
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What happens when the concentration of one of the reactions or products in an equilibrium system is changed?
If the concentration of one of the reactants or products is changed, the system is no longer at equilibrium and the concentrations of all the substances will change until equilibrium is reached again.
If the concentration of one of the reactants or products is changed, the system is no longer at equilibrium and the concentrations of all the substances will change until equilibrium is reached again.
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What happens when the concentration of a reactant is increased in an equilibrium system?
If the concentration of a reactant is increased, more products will be formed until equilibrium is reached again.
If the concentration of a reactant is increased, more products will be formed until equilibrium is reached again.
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What happens when the concentration of a reactant is decreased in an equilibrium system?
If the concentration of a product is decreased, more reactants will react until equilibrium is reached again.
If the concentration of a product is decreased, more reactants will react until equilibrium is reached again.
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What would happen if the concentration of potassium chloride is increase? Cl2(g) H2O(l) (reversible arrow) Cl-(aq) ClO-(aq) 2H (aq)
If potassium chloride (a source of chloride ions) is added to the equilibrium mixture, the equilibrium will shift to the left, to remove the chloride ions added.
Students should be able to interpret appropriate given data to predict the effect of a change in concentration of a reactant or product on given reactions at equilibrium.
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The Haber process is used to manufacture what substance?
The Haber process is used to manufacture ammonia, which can be used to produce nitrogen-based fertilisers.
The Haber process is used to manufacture ammonia, which can be used to produce nitrogen-based fertilisers.
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Write a word equation for the Haber process?
Nitrogen Hydrogen <=> Ammonia
Some of the hydrogen and nitrogen reacts to form ammonia.
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Why does some of the ammonia produced through the Haber process break back down into nitrogen and hydrogen?
Because the reaction is a reversible reaction.
The reaction is reversible so some of the ammonia produced breaks down into nitrogen and hydrogen: nitrogen hydrogen --> <-- ammonia
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Explain how the commercially used conditions for the Haber process are related to the availability and cost of raw materials?
The raw materials for this process are hydrogen and nitrogen. Hydrogen is obtained by reacting natural gas - methane - with steam, or through the cracking of oil. This pathway is used as hydrocarbon compounds contain large percentages of hydrogen and are readily available. Nitrogen is obtained by burning hydrogen in air. Air is used due to being rich in Nitrogen gas (79% nitrogen); nearly all the rest is oxygen. When hydrogen is burned in air, the oxygen combines with the hydrogen, leaving nitrogen behind.
? explain how the commercially used conditions for the Haber process are related to the availability and cost of raw materials and energy supplies, control of equilibrium position and rate
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How is any ammonia created through the Haber process separated from any unreacted nitrogen and hydrogen?
The remaining products are cooled. Ammonia has a much higher boiling point than either hydrogen or nitrogen, so liquefies and is removed. The remaining hydrogen and nitrogen gases are recycled.
On cooling, the ammonia liquefies and is removed. The remaining hydrogen and nitrogen are recycled.
0
Justify why the Haber process is carried out at 200 atmospheres?
The Haber process is a reversible reaction meaning it will reach a dynamic equilibrium As there are fewer molecules of product than reactant, high pressure pushes equilibrium to favour the products and produce a higher yield of ammonia. The reason pressures higher than 200 atmospheres are not used - Substances under extremely high pressure can be dangerous. - Extremely expensive equipment must be used to keep reactants under sustained high pressures. - High amounts of energy are required to pressurise the gas.
MS 1a Recognise and use expressions in decimal form. MS 1c Use ratios, fractions and percentages.
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Justify the use of a high temperature in the Haber process?
The Haber process is a reversible reaction meaning it will reach a dynamic equilibrium The forward reaction is exothermic, so in fact a higher temperature reduces the yield of ammonia. The reason that higher temperatures are used are to increase the rate of reaction, to make the process economically viable.
? apply the principles of dynamic equilibrium in Reversible reactions and dynamic equilibrium to the Haber process
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Suggest why a catalyst is used in the Haber process?
The Haber process is a reversible reaction meaning it will reach a dynamic equilibrium. The use of a catalyst does not affect the position of equilibrium, but will speed up the rate at which it reaches equilibrium.
? explain the trade-off between rate of production and position of equilibrium
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What are the raw materials required for the Haber process?
The raw materials for the Haber process are nitrogen and hydrogen
The raw materials for the Haber process are nitrogen and hydrogen
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What is commonly used as the source of nitrogen in the Haber process? What is commonly used as the source of hydrogen in the Haber process?
Nitrogen gas used in the reaction is taken from the air by reacting the oxygen in the air with hydrogen, leaving nearly pure hydrogen gas. Hydrogen for the reaction is created by reacting natural gas (mostly methane) and steam.
Students should be able to recall a source for the nitrogen and a source for the hydrogen used in the Haber process
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What conditions are used in the Haber process?
- Iron catalyst - High temperature (450C) - High pressure (200 atmospheres)
The purified gases are passed over a catalyst of iron at a high temperature (about 450?C) and a high pressure (about 200 atmospheres).
0
Where does crude oil come from?
Crude oil is a finite resource found in rocks. Crude oil is the remains of an ancient biomass consisting mainly of plankton that was buried in mud.
Crude oil is a finite resource found in rocks. Crude oil is the remains of an ancient biomass consisting mainly of plankton that was buried in mud.
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Is crude oil a mixture of elements, compounds or both?
Crude oil is a mixture of a very large number of compounds called hydrocarbons.
Crude oil is a mixture of a very large number of compounds.
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What is the definition of a hydrocarbon?
Hydrocarbons are molecules made up of hydrogen and carbon atoms only.
Most of the compounds in crude oil are hydrocarbons, which are molecules made up of hydrogen and carbon atoms only.
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Does crude oil contain mostly alkanes or alkenes?
Most of the hydrocarbons in crude oil are hydrocarbons called alkanes
Most of the hydrocarbons in crude oil are hydrocarbons called alkanes. The general formula for the homologous series of alkanes is CnH2n+2
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What are the names of the first four members of alkanes?
The first four members of the alkanes are: methane, ethane, propane and butane.
The first four members of the alkanes are methane, ethane, propane and butane.
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What is the general formula for alkane molecules?
The general formula for the homologous series of alkanes is CnH2n 2.
Alkane molecules can be represented in the following forms: C2H6 or displayed formula.
0
Which of the following are examples of alkanes: C4H10, C2H4, C5H12?
C4H10 and C5H12 are both examples of alkanes.
Students should be able to recognise substances as alkanes given their formulae in these forms.
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Name the alkane with: a) 1 carbon b) 2 carbons c) 3 carbons d) 4 carbons
a) Methane b) Ethane c) Propane d) Butane
Students do not need to know the names of specific alkanes other than methane, ethane, propane and butane.
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How can crude oil be separated into fractions?
The many hydrocarbons in crude oil may be separated into fractions, each of which contains molecules with a similar number of carbon atoms, by fractional distillation.
The many hydrocarbons in crude oil may be separated into fractions, each of which contains molecules with a similar number of carbon atoms, by fractional distillation.
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Why is it useful to separate crude oil into fractions?
The fractions can be processed to produce fuels and feedstock for the petrochemical industry.
The fractions can be processed to produce fuels and feedstock for the petrochemical industry.
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What type of fuels are produced from crude oil?
Many of the fuels on which we depend for our modern lifestyle, such as petrol, diesel oil, kerosene, heavy fuel oil and liquefied petroleum gases, are produced from crude oil.
Many of the fuels on which we depend for our modern lifestyle, such as petrol, diesel oil, kerosene, heavy fuel oil and liquefied petroleum gases, are produced from crude oil.
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What are three examples of useful materials produced by the petrochemical industry?
Many useful materials on which modern life depends are produced by the petrochemical industry, such as solvents, lubricants, polymers, detergents.
Many useful materials on which modern life depends are produced by the petrochemical industry, such as solvents, lubricants, polymers, detergents.
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Why is it possible to produce such a vast array of products from crude oil?
The vast array of natural and synthetic carbon compounds occur due to the ability of carbon atoms to form families of similar compounds.
The vast array of natural and synthetic carbon compounds occur due to the ability of carbon atoms to form families of similar compounds.
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How does fractional distillation separate crude oil into fractions?
Fractional distillation seperates crude oil first by vaporisating all compounds, a column of varying temperatures allows molecules with similar condensation points to be seperated. This is due to their carbon chain length
Students should be able to explain how fractional distillation works in terms of evaporation and condensation.
0
What factor of effects a hydrocarbons boiling point, viscosity and flammability?
The factor that effects a hydrocarbons boiling point, viscosity and flammability is the size of their molecule
Some properties of hydrocarbons depend on the size of their molecules, including boiling point, viscosity and flammability. These properties influence how hydrocarbons are used as fuels. (WS) Investigate the properties of different hydrocarbons.
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How does boiling point, viscosity and flammability change with increasing molecular size?
As molecular size of hydrocarbons increases the boiling point increases, the viscosity increases and flammability decreases.
Students should be able to recall how boiling point, viscosity and flammability change with increasing molecular size.
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What are the products of the complete combustion?
The complete combustion of a hydrocarbon produces carbon dioxide and water.
The complete combustion of a hydrocarbon produces carbon dioxide and water.
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What is the balanced symbol equation for the complete combustion of methane (CH4)? (include state symbols in your answer)
CH4(g) + O2(g) -> CO2(g) + H2O(g)
Students should be able to write balanced equations for the complete combustion of hydrocarbons with a given formula.
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What happens to the carbon and hydrogen atoms during combustion reactions?
During combustion, the carbon and hydrogen in the fuels are oxidised.
During combustion, the carbon and hydrogen in the fuels are oxidised.
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What is the useful outcome of the combustion of hydrocarbon fuels?
The useful outcome of the combustion of hydrocarbon fuels is that it releases energy.
The combustion of hydrocarbon fuels releases energy.
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Describe how the each of the following properties changes as the length of hydrocarbon chains within a fraction increases: a) Boiling point b) Flammability c) Viscosity
a) Boiling point increases as chain length increases. b) Flammability decreases as chain length increases. c) Viscosity increases as chain length increases.
Knowledge of trends in properties of hydrocarbons is limited to: ? boiling points, ? viscosity, ? flammability.
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What is cracking?
Cracking is when hydrocarbons are broken down into smaller more useful molecules
Hydrocarbons can be broken down (cracked) to produce smaller, more useful molecules.
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Describe the conditions required for catalytic cracking?
Hydrocarbons are heated to vaporise them and passed through a hot catalyst breaking down the molecules into smaller ones by thermal decomposition
Cracking can be done by various methods including catalytic cracking and steam cracking.
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How is cracking done using steam?
Hydrocarbons are heated to vaporise them and mixed with steam and heated to very high temperatures breaking down the molecules into smaller ones by thermal decomposition
Students should be able to describe in general terms the conditions used for catalytic cracking and steam cracking.
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What are the products of cracking?
The products of cracking include alkanes and another type of hydrocarbon called alkenes.
The products of cracking include alkanes and another type of hydrocarbon called alkenes.
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What is the balanced equation for the cracking of this alkane? C15H32 --> 2C2H4 C3H6 _______
The balanced equation for the cracking is: C15H32 --> 2C2H4 + C3H6 + C8H18
Students should be able to balance chemical equations as examples of cracking given the formulae of the reactants and products.
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Why do do alkenes react with bromine water, but alkanes don't?
Alkenes react with bromine water because they have a C=C making them more reactive than alkanes (which don?t react with bromine water)
Alkenes are more reactive than alkanes and react with bromine water, which is used as a test for alkenes.
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What is the chemical test and positive result for identifying alkenes?
The chemical test for identifying alkenes is to add bromine water, the positive result is that the bormine was decolourises.
Students should be able to recall the colour change when bromine water reacts with an alkene.
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Why is cracking of hydrocarbons so important?
Cracking is important because there is a high demand for fuels with small molecules and so some of the products of cracking are useful as fuels.
There is a high demand for fuels with small molecules and so some of the products of cracking are useful as fuels.
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How are alkenes used in chemical industry?
Alkenes are used to produce polymers and as starting materials for the production of many other chemicals.
Alkenes are used to produce polymers and as starting materials for the production of many other chemicals.
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How does modern life depend on the uses of hydrocarbons?
Hydrocarbons are used to produce fuels for transport, generating electricity. They are the raw materials for producing plastics and other chemicals.
Students should be able to give examples to illustrate the usefulness of cracking. They should also be able to explain how modern life depends on the uses of hydrocarbons. (For Combined Science: Trilogy and Synergy students do not need to know the formulae or names of individual alkenes.)
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What is the structure of an alkene like?
Alkenes are hydrocarbons (molecules made up of only hydrogen and carbon) with a double carbon-carbon bond.
Alkenes are hydrocarbons with a double carbon-carbon bond.
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What is the general formula for the homologous series of alkenes?
The general formula for the homologous series of alkenes is CnH2n.
The general formula for the homologous series of alkenes is CnH2n. Recognise substances that are alkenes from their names or from given formulae in these forms.
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Why are alkene molecules called unsaturated molecules?
Alkene molecules are unsaturated because they contain two fewer hydrogen atoms than the alkane with the same number of carbon atoms.
Alkene molecules are unsaturated because they contain two fewer hydrogen atoms than the alkane with the same number of carbon atoms.
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What are the conditions for the addition of water to alkenes?
The conditions for the additional of water to alkenes is to use steam passed over a catalyst of hot phosphoric acid. The resulting product is an alcohol.
Students should be able to describe the reactions and conditions for the addition of water alkenes
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What are the conditions for the addition of halogens to alkenes?
If the alkene is a gas the halogen must also be a gas. If the alkene is a liquid then the halogen can be bubbled through as a gas.
Students should be able to describe the reactions and conditions for the addition of halogens to alkenes
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What are the names of the first four members of the homologous series of alkenes?
The first four members of the homologous series of alkenes are ethene, propene, butene and pentene.
The first four members of the homologous series of alkenes are ethene, propene, butene and pentene.
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What is the structural and display formula ethene?
The structural formula for ethene is C2H4, display formula shows C=C with 2 hydrogens bonded to each C by a single bond.
Alkene molecules can be represented in the following forms: C3H6 or displayed formula
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What is the structural and display formula pentene?
The structural formula for ethene is C5H10, display formula shows one C=C anywhere with all other carbons single bonded C-C. There are 10 carbons single bonded, each carbon has four bonds in total.
Students do not need to know the names of individual alkenes other than ethene, propene, butene and pentene.
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What is the functional group for alkenes?
Alkenes are hydrocarbons with the functional group C=C.
Alkenes are hydrocarbons with the functional group C=C.
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What determines the reactions of organic compounds?
It is the generality of reactions of functional groups that determine the reactions of organic compounds.
It is the generality of reactions of functional groups that determine the reactions of organic compounds.
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How does the combustion of alkenes differ in oxygen and in air?
Alkenes react with oxygen in combustion reactions in the same way as other hydrocarbons, but they tend to burn in air with smoky flames because of incomplete combustion.
Alkenes react with oxygen in combustion reactions in the same way as other hydrocarbons, but they tend to burn in air with smoky flames because of incomplete combustion.
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How do alkenes react with hydrogen, water and the halogens?
Alkenes react with hydrogen (in the presence of a nickel catalyst), water (phosphoric acid catalyst) and the halogens, by the addition of atoms across the carbon-carbon double bond so that the double bond becomes a single carbon-carbon bond.
Alkenes react with hydrogen, water and the halogens, by the addition of atoms across the carbon-carbon double bond so that the double bond becomes a single carbon-carbon bond.
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What are the conditions required for the addition of hydrogen to alkenes?
The conditions for the addition of hydrogen to alkenes is 300oC and over a heated catalyst of finely divided nickel
Students should be able to describe the reactions and conditions for the addition of hydrogen to alkenes
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What are the conditions required for the addition of water to alkenes?
The conditions for the addition of water to alkenes is high temperature (for steam) and a phosphoric acid catalyst.
Students should be able to describe the reactions and conditions for the addition of hydrogen to alkenes
0
What are the structures of the following products of alkene addition reactions: 1. dibromoethane 2. dichloroethane 3. ethanol 4. ethane
The structures of the following products of alkene addition reactions are: 1. dibromoethane = CH2BrCH2Br 2. dichloroethane = CH2ClCH2Cl 3. ethanol = C2H5OH 4. ethane = C2H6
Students should be able to draw fully displayed structural formulae of the first four members of the alkenes and the products of their addition reactions with hydrogen, water, chlorine, bromine and iodine.
0
What is the functional group for alochols?
Alcohols contain the functional group -OH.
Alcohols contain the functional group ?OH.
0
What are the names of the first four members of the homologous series of alcohols?
Methanol, ethanol, propanol and butanol are the first four members of a homologous series of alcohols.
Methanol, ethanol, propanol and butanol are the first four members of a homologous series of alcohols. Opportunities when investigating reactions of alcohols.
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What are the names and structural formula for the first four members of the homologous series of alcohols?
The structural formula for the first four members of the homologous series of alochols are: methanol = CH3OH ethanol = CH3CH2OH propanol = CH3CH2CH2OH butanol = CH3CH2CH2CH2OH
Alcohols can be represented in the following forms: CH3CH2OH or displayed formula
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What happens when when alochols react with sodium?
When alcohols react with sodium they produce hydrogen gas
Students should be able to describe what happens when any of the first four alcohols react with sodium
0
Name the following alcohols from their formula: a) C2H5OH b) C3H7OH c) C6H11OH
a) Ethanol b) Propanol c) Hexanol
Students should be able to recognise alcohols from their names from given formulae.
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What happens when when alochol burns in air?
When alcohols are burnt in air they combust to form water and carbon dioxide, releasing energy
Students should be able to describe what happens when any of the first four alcohols react with burn in air
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What pH solutions are formed when alcohols are added to water?
When alcohols are added to water they form a neutral solution (OH- and XH )
Students should be able to describe what happens when any of the first four alcohols are added to water
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What are the main uses of alcohols?
The main uses of alochols are fuels, producing alocholic drinks, cleaning products, making esters
Students should be able to recall the main uses of these alcohols.
0
How can ethanol be produced from sugar?
Aqueous solutions of ethanol are produced when sugar solutions are fermented using yeast.
Aqueous solutions of ethanol are produced when sugar solutions are fermented using yeast.
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What are the conditions used during the fermentation of sugar to produce ethanol?
Fermintation of ethanol from sugar requires water, enzymes from yeast, temperature between 25-40 degress celcius and an absence of oxygen
Students should know the conditions used for fermentation of sugar using yeast.
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What happens when alcohols react with oxidising agents?
When alochols react with oxidising agents they form carboxylic acids
Students should be able to describe what happens when any of the first four alcohols react with an oxidising agent
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What is the functional group for carboxylic acids?
Carboxylic acids have the functional group COOH.
Carboxylic acids have the functional group ?COOH.
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What are the names of the first four members of a homologous series of carboxylic acids?
The first four members of a homologous series of carboxylic acids are methanoic acid, ethanoic acid, propanoic acid and butanoic acid
The first four members of a homologous series of carboxylic acids are methanoic acid, ethanoic acid, propanoic acid and butanoic acid. (WS) Opportunies within investigation of the reactions of carboxylic acids.
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What is the structure of the first four members of a homologous series of carboxylic acids?
the structure of the first four members of a homologous series of carboxylic acids are: 1. methanoic acid = HCOOH 2. ethanoic acid = CH2COOH 3. propanoic acid = C2H5COOH 4. butanoic acid = C3H7COOH
The structures of carboxylic acids can be represented in the following forms: CH3COOH or displayed formula
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What are the names of the following carboxylic acids? 1. HCOOH 2. CH2COOH 3. C2H5COOH 4. C3H7COOH
the structure of the first four members of a homologous series of carboxylic acids are: 1. methanoic acid = HCOOH 2. ethanoic acid = CH2COOH 3. propanoic acid = C2H5COOH 4. butanoic acid = C3H7COOH
Students should be able to recognise carboxylic acids from their names or from given formulae.
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(HT only) Why are carboxylic acids weak acids in terms of ionisation and pH?
Carboxylic acids are weak acids as they exist in an equlibrium so don't ever fully ionise (dissossiate)
(HT only) explain why carboxylic acids are weak acids in terms of ionisation and pH (see Strong and weak acids
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What happens when carboxylic acids react with carbonates?
When carboxylic acids react with carbonates they product carbon dioxide gas
Students should be able to describe what happens when any of the first four carboxylic acids react with carbonates
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What happens when carboxylic acids dissolve in water?
When carboxylic acids dissolve in water they produce acidic solutions
Students should be able to describe what happens when any of the first four carboxylic acids dissolve in water
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What happens when carboxylic acids react with alcohols?
When carboxylic acids react with alochols they produce an ester and water. An acid catalyst is needed.
Students should be able to describe what happens when any of the first four carboxylic acids react with alcohols.
0
What is a pure substance?
A pure substance is a single element or compound, not mixed with any other substance.
In chemistry, a pure substance is a single element or compound, not mixed with any other substance.
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What is a formulation?
A formulation is a mixture that has been designed to have distinct properties and be used as a useful product.
A formulation is a mixture that has been designed as a useful product.
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What can be used to distinguish between pure substances and mixtures?
Use Melting point and boiling point data to distinguish between pure substances and mixtures?
Pure elements and compounds melt and boil at specific temperatures. Melting point and boiling point data can be used to distinguish pure substances from mixtures.
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What are examples of formulations?
Formulations: fuels, cleaning agents, paints, medicines, alloys, fertilisers and foods.
Formulations include fuels, cleaning agents, paints, medicines, alloys, fertilisers and foods.
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What is a pure substance in everyday language?
A pure substance can mean a substance that has had nothing added to it, so it is unadulterated and in its natural state, eg pure milk.
In everyday language, a pure substance can mean a substance that has had nothing added to it, so it is unadulterated and in its natural state, eg pure milk.
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How are formulations made?
They are made by mixing the components in carefully measured quantities to ensure that the product has the required properties.
Formulations are made by mixing the components in carefully measured quantities to ensure that the product has the required properties.
0
How would you test if carbon dioxide was present In a reaction?
Use an aqueous solution of calcium hydroxide (lime water). When carbon dioxide is shaken with or bubbled through limewater the limewater turns milky (cloudy).
The test for carbon dioxide uses an aqueous solution of calcium hydroxide (lime water). When carbon dioxide is shaken with or bubbled through limewater the limewater turns milky (cloudy).
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How would you test if Hydrogen was present In a reaction?
Use a burning splint held at the open end of a test tube of the gas. Hydrogen burns rapidly with a pop sound
The test for hydrogen uses a burning splint held at the open end of a test tube of the gas. Hydrogen burns rapidly with a pop sound
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How would you test if chlorine was present In a reaction?
When damp litmus paper is put into chlorine gas the litmus paper is bleached and turns white.
The test for chlorine uses litmus paper. When damp litmus paper is put into chlorine gas the litmus paper is bleached and turns white.
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How would you test if Oxygen was present In a reaction?
Use a glowing splint inserted into a test tube of the gas. The splint relights in oxygen
The test for oxygen uses a glowing splint inserted into a test tube of the gas. The splint relights in oxygen
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What can Chromatography be used to separate?
Chromatography can be used to separate mixtures such as inks and can give information to help identify the substances from which it is made.
Chromatography can be used to separate mixtures and can give information to help identify substances.
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What are the names of the two phases involved in chromatography?
Stationary phase and mobile phase.
Chromatography involves a stationary phase and a mobile phase.
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What does seperation depend on?
Separation depends on the distribution of substances between the phases.
Separation depends on the distribution of substances between the phases
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How should the Rf value be expressed?
The ratio of the distance moved by a compound (centre of spot from origin) to the distance moved by the solvent
The ratio of the distance moved by a compound (centre of spot from origin) to the distance moved by the solvent can be expressed as its R value
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How is the Rf value calculated?
Rf = distance moved by substance / distance moved by solvent
RT = distance moved by substance / distance moved by solvent
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How do the Rf values of compounds change in different solvents?
Different compounds have different R values in different solvents.
Different compounds have different R values in different solvents,
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How can compounds be identified?
Rf values can be used to help identify the compounds.
Rf values can be used to help identify the compounds.
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How many spots are produced by a pure compound compared to a compound in a mixture?
The compounds in a mixture may separate into different spots depending on the solvent but a pure compound will produce a single spot in all solvents.
The compounds in a mixture may separate into different spots depending on the solvent but a pure compound will produce a single spot in all solvents.
0
How can paper chromatography be used to separate mixtures?
A spot of each mixture is dropped onto the start line of the paper chromotography. The paper chromatogram is introduced to a solvent and left for seperation to take place.
Students should be able to explain how paper chromatography separates mixtures
0
How can chromatographic methods can be used for distinguishing pure substances from impure substances?
The compounds in a mixture may separate into multiple spots depending on the solvent, but a pure substance will always produce a single spot in all solvents.
Students should be able to suggest how chromatographic methods can be used for distinguishing pure substances from impure substances
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How can chromatograms be used to determine R values?
The R value can be calculated and compared. RT = distance moved by substance / distance moved by solvent
Students should be able to interpret chromatograms and determine R values from chromatograms
0
How can elements and compounds be detected?
Elements and compounds can be detected and identified using instrumental methods. Instrumental methods are accurate, sensitive and rapid.
Elements and compounds can be detected and identified using instrumental methods. Instrumental methods are accurate, sensitive and rapid.
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What are the advantages of instrumental methods compared with the chemical tests?
Students should be able to state advantages of instrumental methods compared with the chemical tests in this specification.
0
What are the different colours produced by some metal ions (cations)?
lithium compounds result in a crimson flame ? sodium compounds result in a yellow flame ? potassium compounds result in a lilac flame ? calcium compounds result in an orange-red flame ? copper compounds result in a green flame.
Flame tests can be used to identify some metal ions (cations). Lithium, sodium, potassium, calcium and copper compounds produce distinctive colours in flame tests: ? lithium compounds result in a crimson flame ? sodium compounds result in a yellow flame ? potassium compounds result in a lilac flame ? calcium compounds result in an orange-red flame ? copper compounds result in a green flame.
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When are some flame colours masked?
If a sample containing a mixture of ions
If a sample containing a mixture of ions is used some flame colours can be masked
0
How do carbonates react with dilute acids?
Carbonates react with dilute acids to form carbon dioxide gas. Carbon dioxide can be identified with limewater.
Carbonates react with dilute acids to form carbon dioxide gas. Carbon dioxide can be identified with limewater.
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What do Halide ions produce when they react with silver nitrate solution?
Halide ions in solution produce precipitates with silver nitrate solution in the presence of dilute nitric acid. Silver chloride is white, silver bromide is cream and silver iodide is yellow.
Halide ions in solution produce precipitates with silver nitrate solution in the presence of dilute nitric acid. Silver chloride is white, silver bromide is cream and silver iodide is yellow.
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What do Sulfate ions in solution produce when they react with barium chloride in the presence of hydrochloric acid?
Sulfate ions in solution produce a white precipitate with barium chloride solution in the presence of dilute hydrochloric acid.
Sulfate ions in solution produce a white precipitate with barium chloride solution in the presence of dilute hydrochloric acid.
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What solution can be used to identify some some metal ions (cations)?
Sodium hydroxide solution can be used to identify some metal ions (cations).
Sodium hydroxide solution can be used to identify some metal ions (cations).
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What do solutions of aluminium, calcium and magnesium ions form?
They form white precipitates when sodium hydroxide solution is added but only the aluminium hydroxide precipitate dissolves in excess sodium hydroxide solution.
Solutions of aluminium, calcium and magnesium ions form white precipitates when sodium hydroxide solution is added but only the aluminium hydroxide precipitate dissolves in excess sodium hydroxide solution.
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What happens when sodium hydroxide is added to Solutions of copper(II), iron(II) and iron(III) ions?
Solutions of copper(II), iron(II) and iron(III) ions form coloured precipitates when sodium hydroxide solution is added. Copper(II) forms a blue precipitate, iron(II) a green precipitate and iron(III) a brown precipitate.
Solutions of copper(II), iron(II) and iron(III) ions form coloured precipitates when sodium hydroxide solution is added. Copper(II) forms a blue precipitate, iron(II) a green precipitate and iron(III) a brown precipitate.
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Write a balanced equation for reactions that produce the insoluble hydroxides.
CuSo4 2NaOH Cu(OH)2 Na2SO4
Students should be able to write balanced equations for the reactions to produce the insoluble hydroxides.
0
What is Flame emission spectroscopy used for?
Flame emission spectroscopy is an example of an instrumental method used to analyse metal ions in solutions.
Flame emission spectroscopy is an example of an instrumental method used to analyse metal ions in solutions.
0
What can the output of a line spectrum be used for?
The sample is put into a flame and the light given out is passed through a spectroscope. The output is a line spectrum that can be analysed to identify the metal ions in the solution and measure their concentrations.
The sample is put into a flame and the light given out is passed through a spectroscope. The output is a line spectrum that can be analysed to identify the metal ions in the solution and measure their concentrations.
0
What is the composition of the earths atmosphere?
about four-fifths (approximately 80 %) nitrogen ? about one-fifth (approximately 20 %) oxygen ? small proportions of various other gases, including carbon dioxide, water vapour and noble gases.
Students to recall current composition of the earths atmosphere: about four-fifths (approximately 80 %) nitrogen, about one-fifth (approximately 20 %) oxygen and small proportions of various other gases, including carbon dioxide, water vapour and noble gases.
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How has the Earths atmosphere evolved?
One theory suggests that during the first billion years of the Earth?s existence there was intense volcanic activity that released gases that formed the early atmosphere and water vapour that condensed to form the oceans. At the start of this period the Earth?s atmosphere may have been like the atmospheres of Mars and Venus today, consisting of mainly carbon dioxide with little or no oxygen gas.
Students should be able to, given appropriate information, interpret evidence and evaluate different theories about the Earth's early atmosphere.
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How has the Earths atmosphere evolved?
One theory suggests that during the first billion years of the Earth?s existence there was intense volcanic activity that released gases that formed the early atmosphere and water vapour that condensed to form the oceans. At the start of this period the Earth?s atmosphere may have been like the atmospheres of Mars and Venus today, consisting of mainly carbon dioxide with little or no oxygen gas.
One theory suggests that during the first billion years of the Earth's existence there was intense volcanic activity that released gases that formed the early atmosphere and water vapour that condensed to form the oceans. At the start of this period the Earth's atmosphere may have been like the atmospheres of Mars and Venus today, consisting of mainly carbon dioxide with little or no oxygen gas.
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What types of gases did volcanoes produce?
Volcanoes produced nitrogen which gradually built up in the atmosphere and there may have been small proportions of methane and ammonia.
Volcanoes also produced nitrogen which gradually built up in the atmosphere and there may have been small proportions of methane and ammonia.
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What happened to the atmopshere when the oceans formed?
When the oceans formed carbon dioxide dissolved in the water and carbonates were precipitated producing sediments, reducing the amount of carbon dioxide in the atmosphere.
When the oceans formed carbon dioxide dissolved in the water and carbonates were precipitated producing sediments, reducing the amount of carbon dioxide in the atmosphere. No knowledge of other theories is required.
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What process has caused oxygen levels in our atmosphere to increase since its formation?
Photosynthesis, carried out by organisms such as algae and plants converted carbon dioxide into the oxygen now found in the atmosphere.
Algae and plants produced the oxygen that is now in the atmosphere by photosynthesis, which can be represented by the equation.
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When did Algae first produce oxygen?
Algae first produced oxygen about 2.7 billion years ago and soon after this oxygen appeared in the atmosphere. Over the next billion years plants evolved and the percentage of oxygen gradually increased to a level that enabled animals to evolve.
Algae first produced oxygen about 2.7 billion years ago and soon after this oxygen appeared in the atmosphere. Over the next billion years plants evolved and the percentage of oxygen gradually increased to a level that enabled animals to evolve.
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How did Algae and plants affect the atmosphere?
Algae and plants decreased the percentage of carbon dioxide in the atmosphere by photosynthesis.
Algae and plants decreased the percentage of carbon dioxide in the atmosphere by photosynthesis.
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Apart from through the process of photosynthesis, what else has caused carbon dioxide levels in the atmosphere to decrease since its formation?
Carbon dioxide levels also decreased due to some dissolving into the oceans, the formation of sedimentary rocks and the formation of fossil fuels.
Carbon dioxide was also decreased by the formation of sedimentary rocks and fossil fuels that contain carbon.
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How did the Earth's atmosphere change over time? Why did these changes happen?
Volcanic activity caused high levels of carbon dioxide, as the volancos died out the Earth's temperature cooled. The water vapour produced by volcanos condensed to form oceans. The carbon dioxide levels decreased as it dissolved into the oceans and formed part of the shells of marine animals.
Students should be able to describe the main changes in the atmosphere over time and some of the likely causes of these changes
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How and why did limestone, coal, crude oil and natural gas form?
Limestone, crude oil and natural gas all contain carbon. Limestone was formed by the calcium carbonate from sea organisms and their shells. Crude oil and natural gas form from the decomposition of living animals and plants.
Students should be able to describe and explain the formation of deposits of limestone, coal, crude oil and natural gas.
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How does the atmosphere help the Earth maintain stable surface temperatures?
Greenhouse gases in the atmosphere maintain temperatures on Earth high enough to support life. Water vapour, carbon dioxide and methane are greenhouse gases.
Oreenhouse gases in the atmosphere maintain temperatures on Earth high enough to support life. Water vapour, carbon dioxide and methane are greenhouse gases.
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What are the long and short term impacts of the greenhouse effect?
Short term effects: Average surface temperature of earth increases. Long term effect: Rising sea levels, more extreme weather patterns.
Students should be able to describe the greenhouse effect in terms of the interaction of short and long wavelength radiation with matter.
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What types of human activities increase the amounts of greenhouse gases in the atmosphere?
Any human activity that produces carbon dioxide and methane.
Some human activities increase the amounts of greenhouse gases in the atmosphere. These include: - carbon dioxide - methane. Students should be able to recall two human activities that increase the amounts of each of the greenhouse gases carbon dioxide and methane.
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What do most scientists believe will happen to the Earth?s atmosphere?
Many scientists believe that human activities will cause the temperature of the Earth?s atmosphere to increase at the surface and that this will result in global climate change.
Based on peer-reviewed evidence, many scientists believe that human activities will cause the temperature of the Earth's atmosphere to increase at the surface and that this will result in global climate change.
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What difficulties can such complex systems as global climate change cause?
They lead to simplified models, speculation and opinions presented in the media that may be based on only parts of the evidence and which may be biased.
There are difficulties in such complex systems as global climate change. This leads to simplified models, speculation and opinions presented in the media that may be based on only parts of the evidence and which may be biased.
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What is the importance of peer reviewing results and of communicating results to a wide range of audiences.
Peer reviewing is important within the science community as it prevents bias and allows links to be made within and outside certain specialisms as well as to educate wider audiances.
Students should be able to recognise the importance of peer review of results and of communicating results to a wide range of audiences.
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What is a major cause of climate change?
An increase in average global temperature is a major cause of climate change.
An increase in average global temperature is a major cause of climate change. There are several potential effects of global climate changes.
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Describe briefly four potential effects of global climate change
The potential effects of global climate change are rising sea levels, damage to ozone layer, increase earth temperature, polar ice caps melting, animals may become extinct, damage to coral reefs.
Students should be able to describe briefly four potential effects of global climate change
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What are the scale, risk and environmental implications of global climate change.
Global scale with different affects in different regions. Risk to lost of home, crops, spread of disease, more extreme weather events such as hurricanes and flooding and species extinction.
Students should be able to discuss the scale, risk and environmental implications of global climate change.
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What is a carbon footprint?
The carbon footprint is the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event.
The carbon footprint is the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event.
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How can a carbon footprint be reduced?
The carbon footprint can be reduced by reducing emissions of carbon dioxide and methane.
The carbon footprint can be reduced by reducing emissions of carbon dioxide and methane.
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What actions are required to reduce emissions of carbon dioxide and methane?
The main way to reduce emissions of carbon dioxide in the air is to burn less fossil fuels. Unfortunately, we depend on the burning of fossil fuels for heating, electricity generation and transport. If we are to burn less fossil fuels, we will need alternatives for these essential activities. Cattle farming produces a vast quantity of methane and therefore an effective way to reduce the emissions of methane would be o move away from a meat based diet towards a more plant based diet. This would also be a more effective use of land as the land used to produce cattle feed could be used to grow crops and vegetables.
Students should be able to describe actions to reduce emissions of carbon dioxide and methane
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What human activity is the biggest contributor to an increase in atmospheric pollutants?
The combustion of fossil fuels is a major source of atmospheric pollutants.
The combustion of fuels is a major source of atmospheric pollutants.
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What do most fuels contain?
Most fuels, including coal, contain carbon and/or hydrogen and may also contain some sulfur.
Most fuels, including coal, contain carbon and/or hydrogen and may also contain some sulfur.
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Name the gases commonly released into the atmosphere when a fuel is burned?
Carbon dioxide, water vapour, carbon monoxide, sulfur dioxide and oxides of nitrogen. Solid particles and unburned hydrocarbons may also be released that form particulates in the atmosphere.
The gases released into the atmosphere when a fuel is burned may include carbon dioxide, water vapour, carbon monoxide, sulfur dioxide and oxides of nitrogen. Solid particles and unburned hydrocarbons may also be released that form particulates in the atmosphere.
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How does burning fuels produce carbon monoxide, soot (carbon particles), sulfur dioxide and oxides of nitrogen?
Carbon monoxide is produced through incomplete combustion due to limited oxygen. Soot is produced from carbon that has not reacted during combustion. Sulfur dioxide is produced due to sulfur in the fuel reacting with oxygen in hot enginges. Nirtogen oxides are formed from nitrogen in the air reacting with oxygen.
Students should be able to describe how carbon monoxide, soot (carbon particles), sulfur dioxide and oxides of nitrogen are produced by burning fuels.
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What are the impacts of emissions of carbon monoxide?
Carbon monoxide is a toxic gas. It is colourless and odourless and so is not easily detected.
Carbon monoxide is a toxic gas. It is colourless and odourless and so is not easily detected.
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What environmental impact does the emission of sulfur dioxide and oxides of nitrogen cause?
Sulfur dioxide and oxides of nitrogen cause respiratory problems in humans and cause acid rain.
Sulfur dioxide and oxides of nitrogen cause respiratory problems in humans and cause acid rain.
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What environmental impact do particulates cause?
Particulates cause global dimming and health problems for humans.
Particulates cause global dimming and health problems for humans.
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Describe and explain the problems caused by increased amounts of the following pollutants in the atmosphere: a) Carbon Dioxide b) Nitrogen Oxides c) Sulfur Dioxide d) Particulates
a) Greenhouse gas that contributes to global warming. b) Dissolves in water droplets in clouds, it makes the rain more acidic than normal. This is called acid rain. c) Same as b) d) Very small pieces of solids, mainly carbon, that are released into the air during incomplete combustion. Contribute towards global dimming (the reduction of sunlight that makes it to the earths surface).
Students should be able to describe and explain the problems caused by increased amounts of these pollutants in the air.
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What do humans use the Earth's resources for?
Humans use the Earth's resources to provide warmth, shelter, food and transport.
Humans use the Earth's resources to provide warmth, shelter, food and transport.
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What do natural resources provide?
Natural resources, supplemented by agriculture, provide food, timber, clothing and fuels.
Natural resources, supplemented by agriculture, provide food, timber, clothing and fuels.
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What are finite resources used for?
Finite resources from the Earth, oceans and atmosphere are processed to provide energy and materials.
Finite resources from the Earth, oceans and atmosphere are processed to provide energy and materials.
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What role has Chemistry played in improving agricultural and industrial processes?
Chemistry plays an important role in improving agricultural and industrial processes toprovide new products and in sustainable development, which is development that meets the needs of current generations without compromising the ability of future generations to meet their own needs.
Chemistry plays an important role in improving agricultural and industrial processes to provide new products and in sustainable development, which is development that meets the needs of current generations without compromising the ability of future generations to meet their own needs.
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What are the names of natural products that are supplemented or replaced by agricultural and synthetic products?
The natural products that are supplemented/replaced by agricultural or synthetic products are nitrogen, phosphorus and potassium.
Students should be able to state examples of natural products that are supplemented or replaced by agricultural and synthetic products.
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What is the difference between finite and renewable resources?
Finite resources are those which are limited. Renewable resources are those which can be replenished at the same rate that they are used up.
Students should be able to distinguish between finite and renewable resources given appropriate information.
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What are orders of magnitude?
A system of classification determined by size, typically in powers of ten.
Students should be able to use orders of magnitude to evaluate the significance of data.
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What different aspects of a products lifetime are assessed through a life cycle assessment?
Life cycle assessments (LCAs) are carried out to assess the environmental impact of products in each of these stages: - extracting and processing raw materials - manufacturing and packaging - use and operation during its lifetime - disposal at the end of its useful life, including transport and distribution at each stage.
Life cycle assessments (LCAs) are carried out to assess the environmental impact of products in each of these stages: - extracting and processing raw materials - manufacturing and packaging - use and operation during its lifetime - disposal at the end of its useful life, including transport and distribution at each stage.
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Why are life cycle assessment not a purely objective process?
Life cycle assessments are not a purely objective process because allocating numerical values to pollutant effects is less straightforward and requires value judgments.
Use of water, resources, energy sources and production of some wastes can be fairly easily quantified. Allocating numerical values to pollutant effects is less straightforward and requires value judgements, so LCA is not a purely objective process.
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Why is it important that life cycle assessments are completed by an unbiased impartial agency?
It is important that life cycle assessments are completed using an unbiased impartial agency to avoid misuse of data to reach pre-determined conclusions. e.g. to support a claim that a product is more environmentally friendly.
Selective or abbreviated LCAs can be devised to evaluate a product but these can be misused to reach pre-determined conclusions, eg in support of claims for advertising purposes.
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What are the life cycle assessments that would be conducted for plastic and paper carrier bags?
The life cycle assessments that would be conducted for plastic and paper bags are the raw materials, manufacturing processing, which lasts longer, disposal, transport, emissions and waste.
Students should be able to carry out simple comparative LCAs for shopping bags made from plastic and paper.
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What are the reasons behind the incentive Reduce, Reuse, Recycle?
Reduce, Reuse and Recycle is targeted to end users to reduce the use of limited resources, use of energy sources, waste and environmental impacts.
The reduction in use, reuse and recycling of materials by end users reduces the use of limited resources, use of energy sources, waste and environmental impacts.
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Where are the raw materials found to produce products such as ceramics, metals and plastics?
The raw materials we use to make ceramics, metals and plastics are found within the earths crust.
Metals, glass, building materials, clay ceramics and most plastics are produced from limited raw materials.
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Describe how the majority of energy is generated in order to process raw materials such as clay ceramics and metal ores?
Most energy used to process natural resources is generated from finite resources, such as fossil fuels.
Much of the energy for the processes comes from limited resources.
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Evaluate the environmental impacts of quarrying in order to obtain natural resources
The Environmental impacts of quarrying can be: Once usage is complete, often old quarries can become u - Destruction of natural habitats - Pollutants released from use of chemicals and burning fossil fuels in operation of quarry - Permanently disfigure the local environment and are often visible from long distances
Obtaining raw materials from the Earth by quarrying and mining causes environmental impacts.
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Give an example of a product that can be reused and a product that can be recycled.
Some products, such as glass bottles, can be reused. Glass bottles can be crushed and melted to make different glass products. Other products cannot be reused and so are recycled for a different use such as plastics and metals.
Some products, such as glass bottles, can be reused. Glass bottles can be crushed and melted to make different glass products. Other products cannot be reused and so are recycled for a different use.
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How can metals be recycled?
Metals can be recycled by melting and recasting or reforming into different products.
Metals can be recycled by melting and recasting or reforming into different products.
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What does the amount of separation for a product rely on? Give an example.
The amount of separation required for recycling depends on the material and the properties required of the final product. For example, some scrap steel can be added to iron from a blast furnace to reduce the amount of iron that needs to be extracted from iron ore.
The amount of separation required for recycling depends on the material and the properties required of the final product. For example, some scrap steel can be added to iron from a blast furnace to reduce the amount of iron that needs to be extracted from iron ore.
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What ways can reducing the use of limited resources be achieved?
Reducing the use of limited resources be achieved by producing less waste, reusing certain products, recycling certain products.
Students should be able to evaluate ways of reducing the use of limited resources, given appropriate information.
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What should the quality of drinking water be like?
The quality of drinking water should have low levels of dissolved salts and microbes.
Water of appropriate quality is essential for life. For humans, drinking water should have sufficiently low levels of dissolved salts and microbes.
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What must be done to the waste water produced by urban lifestyles and industrial processes before it can be released back into the environment?
Urban lifestyles and industrial processes produce large amounts of waste water that require treatment before being released into the environment.
Urban lifestyles and industrial processes produce large amounts of waste water that require treatment before being released into the environment.
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What is the name given to water that is safe to drink?
The name given to water that is safe to drink is potable water.
Water that is safe to drink is called potable water. Potable water is not pure water in the chemical sense because it contains dissolved substances.
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What will be required to be removed from a) agricultural waste water and b)industrial waste water?
Agricultural waste water require removal of organic matter and harmful microbes. Industrial waste water may require removal of organic matter and harmful chemicals.
Sewage and agricultural waste water require removal of organic matter and harmful microbes. Industrial waste water may require removal of organic matter and harmful chemicals.
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What factors decide which methods are used to produce potable water?
The methods used to produce potable water depend on available supplies of water and local conditions.
The methods used to produce potable water depend on available supplies of water and local conditions.
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What does sewage treatment include?
Sewage treatment includes: - screening and grit removal - sedimentation to produce sewage sludge and effluent - anaerobic digestion of sewage sludge - aerobic biological treatment of effluent.
Sewage treatment includes: ? screening and grit removal ? sedimentation to produce sewage sludge and effluent ? anaerobic digestion of sewage sludge ? aerobic biological treatment of effluent.
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What stages do most of the potable water in the UK produced?
The stages that most potable water is produced in the UK is: - choosing an appropriate source of fresh water - passing the water through filter beds - sterilising.
In the United Kingdom (UK), rain provides water with low levels of dissolved substances (fresh water) that collects in the ground and in lakes and rivers, and most potable water is produced by: - choosing an appropriate source of fresh water - passing the water through filter beds - sterilising.
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How is potable water obtained from a) waste ground and b) salt water?
Potable water can be obtained from waste ground through the three main stages of sedimentation, filtration and sterilizing. Potable water can be obtained from salt water through desalination by distillation or reverse osmosis.
Students should be able to comment on the relative ease of obtaining potable water from waste, ground and salt water.
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What are three types of sterilising agents used for potable water?
Sterilising agents used for potable water include chlorine, ozone or ultraviolet light.
Sterilising agents used for potable water include chlorine, ozone or ultraviolet light.
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What process can be used to make salt water / sea water potable when fresh water is limited?
If supplies of fresh water are limited, desalination of salty water or sea water may be required.
If supplies of fresh water are limited, desalination of salty water or sea water may be required.
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How is desalination completed? (give two methods)
Desalination can be done by distillation or by processes that use membranes such as reverse osmosis.
Desalination can be done by distillation or by processes that use membranes such as reverse osmosis.
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What is the main drawback of desalination processes?
Desalination processes require large amounts of energy.
These processes require large amounts of energy.
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What is the difference between potable and pure water?
Pure water only contains water particles with no other substances. Potable water is safe to drink but contains other soluble ions.
Students should be able to distinguish between potable water and pure water.
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What is the differences in the way that ground water and salty water is treated?
Salty water is treated by distillation or by reverse osmosis. Ground water is treated by - passing the water through filter beds and then sterilising using chlorine, ozone or UV light.
Students should be able to describe the differences in treatment of ground water and salty water.
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What are the reasons for each step of producing potable water from ground water?
Potable water is filtered to remove any fine particles in the water. It is then steralised to kill microbes.
Students should be able to give reasons for the steps used to produce potable water.
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How can analysis of the purity of water be carried out?
It is possible to analyse the purity of water by the boiling point. The closer the boiling point is to that of pure water, the more pure it is.
Students should be able to carry out analysis and purification of water samples from different sources, including pH, dissolved solids and distillation.
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What will happen to the Earth's supplies of metal ores if we continue to extract them at the rate we are now?
The Earth's resources of metal ores are limited. Eventually they will run out.
The Earth?s resources of metal ores are limited.
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What are new ways of extracting copper from low-grade ores called?
Copper ores are becoming scarce and new ways of extracting copper from low-grade ores include phytomining, and bioleaching.
Copper ores are becoming scarce and new ways of extracting copper from low-grade ores include phytomining, and bioleaching.
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What do these new methods of copper extraction avoid?
These methods avoid traditional mining methods of digging, moving and disposing of large amounts of rock.
These methods avoid traditional mining methods of digging, moving and disposing of large amounts of rock.
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How is phytomining carried out?
Phytomining uses plants to absorb metal compounds. The plants are harvested and then burned to produce ash that contains metal compounds.
Phytomining uses plants to absorb metal compounds. The plants are harvested and then burned to produce ash that contains metal compounds.
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How is bioleaching carried out?
Bioleaching uses bacteria to produce leachate solutions that contain metal compounds.
Bioleaching uses bacteria to produce leachate solutions that contain metal compounds.
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How can copper compounds be processed to obtain the metal.
The metal compounds can be processed to obtain the metal. For example, copper can be obtained from solutions of copper compounds by displacement using scrap iron or by electrolysis.
The metal compounds can be processed to obtain the metal. For example, copper can be obtained from solutions of copper compounds by displacement using scrap iron or by electrolysis.
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What uses do we have for the ammonia produced through the Haber process?
Ammonia can be used to manufacture ammonium salts (used in fertilisers) and nitric acid.
Ammonia can be used to manufacture ammonium salts and nitric acid.
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Recall the names of the salts produced when phosphate rock is treated with: a) nitric acid b) sulfuric acid c) phosphoric acid
a) Calcium nitrate b) Single superphosphate (a mixture of calcium sulfate and calcium phosphate) c) Triple superphosphate (calcium phosphate)
Students should be able to recall the names of the salts produced when phosphate rock is treated with nitric acid, sulfuric acid and phosphoric acid
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What process is used to extract rocks containing phosphate compounds from the earth?
Mining. - The phosphate containing rocks must be processed further prior to being used in fertilisers.
Potassium chloride, potassium sulfate and phosphate rock are obtained by mining, but phosphate rock cannot be used directly as a fertiliser
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How can rocks containing phosphate compounds be treated, in order to make soluble salts that can be used as fertilisers?
Phosphate rock is treated with nitric acid or sulfuric acid to produce soluble salts that can be used as fertilisers.
Phosphate rock is treated with nitric acid or sulfuric acid to produce soluble salts that can be used as fertilisers.
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NPK fertilisers all contain which 3 elements?
N = Nitrogen P = Phosphorus K = Potassium
Compounds of nitrogen, phosphorus and potassium are used as fertilisers to improve agricultural productivity. NPK fertilisers contain compounds of all three elements.
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Can NPK fertilisers be made using a variety of raw materials and different reactions?
Yes, Industrial production of NPK fertilisers can be achieved using a variety of raw materials in several integrated processes
Industrial production of NPK fertilisers can be achieved using a variety of raw materials in several integrated processes
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NPK fertilisers are formulations of various salts. What is a formulation?
Any mixture or substance prepared according to a particular formula. NPK fertilisers are formulations of various salts containing appropriate percentages of the elements (nitrogen, phosphorus and potassium).
NPK fertilisers are formulations of various salts containing appropriate percentages of the elements.
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How can corrosion be described?
Corrosion is the destruction of materials by chemical reactions with substances in the environment.
Corrosion is the destruction of materials by chemical reactions with substances in the environment.
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How can corrosion be prevented?
Corrosion can be prevented by applying a coating that acts as a barrier, such as greasing, painting or electroplating.
Corrosion can be prevented by applying a coating that acts as a barrier, such as greasing, painting or electroplating.
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What practical could be carried out to investigate the conditions needed for corrosion (rusting)?
A practical where a metal object e.g. a nail is kept in different conditions for example: 1. Only in air 2. Only in water 3. In air and water This would show that both air and water are needed for rusting to occur.
Students should be able to describe experiments and interpret results to show that both air and water are necessary for rusting.
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What conditions are needed for corrosion to occur?
Rusting is an example of corrosion. Both air and water are necessary for iron to rust.
Rusting is an example of corrosion. Both air and water are necessary for iron to rust.
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What does sacrificial protection mean?
Some coatings are reactive and contain a more reactive metal to provide sacrificial protection, eg zinc is used to galvanise iron.
Some coatings are reactive and contain a more reactive metal to provide sacrificial protection, eg zinc is used to galvanise iron.
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How is aluminium protected from further corrosion?
Aluminium has an oxide coating that protects the metal from further corrosion.
Aluminium has an oxide coating that protects the metal from further corrosion.
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Would a more or less reactive metal be used in sacrificial protection? Give a reason for your answer.
A more reactive metal is used as this would prevent the less reactive metal from rusting and become weakened.
Students should be able to explain sacrificial protection in terms of relative reactivity.
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Are most everyday metals pure or alloys?
Most metals in everyday use are alloys.
Most metals in everyday use are alloys.
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What are the alloys bronze and brass made up of?
Bronze is an alloy of copper and tin. Brass is an alloy of copper and zinc.
Bronze is an alloy of copper and tin. Brass is an alloy of copper and zinc.
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What is the percentage of gold in 24 carat and 18 carat gold used for jewellery?
The proportion of gold in the alloy is measured in carats. 24 carat being 100 % (pure gold), and 18 carat being 75 % gold.
Gold used as jewellery is usually an alloy with silver, copper and zinc. The proportion of gold in the alloy is measured in carats. 24 carat being 100 % (pure gold), and 18 carat being 75 % gold.
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What elements are present in the alloy steel?
Steels are alloys of iron that contain specific amounts of carbon and other metals.
Steels are alloys of iron that contain specific amounts of carbon and other metals.
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How are the physical properties of high carbon and low carbon steels different?
High carbon steel is strong but brittle. Low carbon steel is softer and more easily shaped.
High carbon steel is strong but brittle. Low carbon steel is softer and more easily shaped.
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What are the benefits of stainless steels that contain chromium and nickel?
Steels containing chromium and nickel (stainless steels) are hard and resistant to corrosion.
Steels containing chromium and nickel (stainless steels) are hard and resistant to corrosion.
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What are the uses of low density aluminium alloys?
The uses of low density alloys can be for building bike frames and aeroplanes.
Aluminium alloys are low density.
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What are the uses of high density steels?
High density steels are used for building materials. Low density steels are used
Students should be able to recall a use of each of the alloys specified.
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How is soda-glass made?
Soda glass is made by heating a mixture of sand, sodium carbonate and limestone.
Most of the glass we use is soda-lime glass, made by heating a mixture of sand, sodium carbonate and limestone.
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How is borosilicate glass made and what is the advantage of it over soda-glass?
Borosilicate glass, made from sand and boron trioxide, melts at higher temperatures than soda-lime glass.
Borosilicate glass, made from sand and boron trioxide, melts at higher temperatures than soda-lime glass.
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How are clay ceramics made?
Clay ceramics, including pottery and bricks, are made by shaping wet clay and then heating in a furnace.
Clay ceramics, including pottery and bricks, are made by shaping wet clay and then heating in a furnace.
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What is a composite and how are they made?
Most composites are made of two materials, a matrix or binder surrounding and binding together fibres or fragments of the other material, which is called the
Most composites are made of two materials, a matrix or binder surrounding and binding together fibres or fragments of the other material, which is called the reinforcement.
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What are three examples of composites?
Some examples of composites are: 1. carbon fibre 2. plywood 3. reinforced concrete 4. Ceramic
Students should be able to recall some examples of composites.
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What is a polymer?
A polymer is a large chain of monomers covalently bonded.
Students should be able to, given appropriate information explain how the properties of materials are related to their uses and select appropriate materials.
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What factors determine the type of polymers that are made?
The properties of polymers depend on what monomers they are made from and the conditions under which they are made. For example, low density (LD) and high density (HD) poly(ethene) are produced from ethene.
The properties of polymers depend on what monomers they are made from and the conditions under which they are made. For example, low density (LD) and high density (HD) poly(ethene) are produced from ethene.
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What is the difference between thermo softening and thermosetting polymers?
Thermosoftening polymers melt when they are heated. Thermosetting polymers do not melt when they are heated.
Thermosoftening polymers melt when they are heated. Thermosetting polymers do not melt when they are heated.
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How are high density and low density poly(ethene) are produced from ethene?
High and Low density poly(ethene) are made using different catalysts and different reaction conditions.
Students should be able to explain how low density and high density poly(ethene) are both produced from ethene.
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How are the structures of thermosoftening and thermosetting polymers different?
Thermosoftening polymers are no cross chains or branches between the polymer chains so slide easily past each other, this makes them change shape when heated. Thermosetting polymers have many cross chains or branches so are able to hold their sh
Students should be able to explain the difference between thermosoftening and thermosetting polymers in terms of their structures.
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What are the properties of solids?
Solids hold their shape.
Solids fill their containers.
Solids take the shape of the bottom of their container.
Solids shape of the shape of top of their container.
Solids hold their shape.
1
What are the properties of liquids?
Liquids take the shape of the bottom of their container.
Liquids hold their shape.
Liquids fill their containers.
Liquids shape of the top of their container.
Liquids take the shape of the bottom of their containers.
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What are the properties of gases?
Gases fill their containers.
Gases take the shape of the bottom of their container.
Gases hold their shape.
Gases take the shape of the top of their container.
Gases fill their containers.
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What is a fluid?
Fluids are liquids and gases because they can flow.
Fluids are solid and gases because they can float.
Fluids are liquids and solid because they can flow.
Fluids are liquids and gases because they can float.
Liquids and gases are known as fluids because they can flow.
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What is anything with mass made of?
All matter (stuff) is made of particles.
All matter (stuff) is made of particles.
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How are the particles arranged in solids?
Particles in a solid form a lattice - regular pattern.
Particles in a solid are spread out and have no pattern.
Particles in a solid are touching, but have no pattern.
Particles in a solid are split.
Particles in a solid form a lattice - regular pattern.
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How are the particles arranged in liquids?
Particles in a liquid are touching, but have no pattern.
Particles in a liquid form a lattice - regular pattern.
Particles in a liquid are spread out and have no pattern.
Particles in a liquid are split.
Particles in a liquid are touching, but have no pattern.
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How are the particles arranged in gases?
Particles in a gas are spread out and have no pattern.
Particles in a gas are touching, but have no pattern.
Particles in a gas form a lattice - regular pattern.
Particles in a gas are split.
Particles in a gas are spread out, with no pattern.
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What property do substances which have particles that are able to move relative to each other have?
They are able to flow (occurs in both liquids and gases).
When particles can move relative to each other, the material can flow.
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What is density?
Density is the how heavy a material is for a given size/the ratio of mass to volume.
Lower: Density is the how heavy a material is for a given size. Higher: Density is the ratio of mass to volume.
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How can we use the a eureka can to measure the volume of an object?
Fill the eureka can with water and then place the object of interest into it. Measure the volume of water that is displaced.
Measure the mass and volume of material sample blocks / objects using eureka cans. Calculate density. Conversion of units and the use of unit prefixes.
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How does the density change between solid, liquid and gas?
- Solids are the most dense; - Gases are the least dense; - With liquids between.
- Gases are the most dense; - Solids are the least dense; - With liquids between.
- Solids are the most dense; - Liquids are the least dense; - With gases between.
- Gases are the most dense; - Liquids are the least dense; - With solids between.
For the same material: - Solids are the most dense; - Gases are the least dense; - With liquids between.
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What happens when a solid is heated but does not yet melt?
Matter expands when heated so becomes less dense.
Matter contracts when heated so becomes less dense.
Matter contracts when heated so becomes more dense.
Matter expands when heated so becomes more dense.
So what happens when a solid is heated but does not yet melt: Matter expands when heated Matter becomes less dense when heated.
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What happens to particles when they are heated?
Particles move faster when heated, and so occupy a larger space.
Particles move faster when heated, and so occupy a smaller space.
Particles move slower when heated, and so occupy a larger space.
Particles move slower when heated, and so occupy a smaller space.
Particles move faster when heated, and so occupy a larger space. Particles do not change size, but can be of different sizes.
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What happens to the force of collision of particles when heated?
When heated, the forces involved in collisions increases as the particles are moving faster.
When heated, the forces involved in collisions decreases as the particles are moving faster.
When heated, the forces involved in collisions increases as the particles are moving slower.
When heated, the forces involved in collisions decreases as the particles are moving slower.
When heated, the forces involved in collisions increases as the particles are moving faster.
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At what temperature would particles ever be stationary?
Particles are never stationary - other than at absolute zero There is nothing in the gaps between particles.
Particles are never stationary - other than at absolute zero There is nothing in the gaps between particles.
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What common chemical is an anomaly and actually less dense as a solid?
The anomaly of ice-water transition: This is why ice floats on water and a full bottle of water breaks in a freezer. It expands and becomes less dense when freezing to a solid.
DESIRABLE: The anomaly of ice-water transition: Less dense objects float. If solids are more dense than liquids, why does ice float on water? Why does a full bottle of water break when left in a freezer? Ice is less dense than water.
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What are the processes of a solid turning into a liquid and a liquid turning into a gas called? What are the processes called changing from a gas to a liquid?
The process of a solid turning into a liquid is called melting. The process of a liquid turning into a solid is called freezing. The process of a liquid turning into a gas is called evaporation. The process of a gas turning into a liquid is called condensation.
The process of a solid turning into a liquid is called melting. The process of a liquid turning into a solid is called freezing. The process of a liquid turning into a gas is called evaporation. The process of a gas turning into a liquid is called condensation.
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What is the process of a solid turning into a gas called?
The process of a solid turning into a gas is called sublimation.
The process of a solid turning into a gas is called evaporation.
The process of a solid turning into a gas is called condensation.
The process of a solid turning into a gas is called deposition.
The process of a solid turning into a gas is called sublimation. These are all changes of state, as solid, liquid and gas are known as 'states of matter'.
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Do uncharged particles attract or repel each other?
Particles always attract each other.
Particles always attract each other.
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How do the forces of attraction and collision determine the state of matter?
Solids exist when the attraction between particles is greater than the forces involved in collisions. Gases exist when the attraction between particles is less than the forces involved in collisions.
Solids exist when the attraction between particles is greater than the forces involved in collisions. Gases exist when the attraction between particles is less than the forces involved in collisions.
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Why are liquids able to pour and take the shape of their containers?
Liquids can pour and take the shape of their container because particles are able to change places with each other. This is what causes the lack of a pattern.
Liquids can pour and take the shape of their container because particles are able to change places with each other. This is what causes the lack of a pattern.
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What effect does energy have on the forces of attraction during melting?
Liquids exists when some particles temporarily get enough energy to over come the forces of attraction with its neighbour and so change places with each other.
Liquids exist when some particles temporarily get enough energy to over come the forces of attraction with its neighbour and so change places with each other.
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How does the mass of water change as an ice cube melts?
The mass of water stays the same as an ice cube melts.
The mass of water increases as an ice cube melts.
The mass of water decreases as an ice cube melts.
The change in mass of water is random as an ice cube melts.
Make a prediction of the change in mass when an Ice cube melts. Develop into an explained hypothesis.
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What does the term 'conservation of mass' mean?
Particles can not be created or destroyed.
Particles can not be created or destroyed.
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Why does the mass change during evaporation?
Although there are no particles destroyed during evaporation, once a gas the particle can not be measured by the balance.
There is a conservation of material and of mass for physical processes ie: in melting, freezing, evaporation, sublimation, condensation. NB: Students have not studied chemical reactions yet.
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How can we represent the changes of state in diagram form?
Check for number of particles being constant; Label melting, freezing, evaporation, sublimation, condensation.
Draw a labelled diagram to show the particle arrangement for a material sample as a solid, liquid and gas. Like: http://www.chemistry.wustl.edu/~edudev/LabTutorials/Thermochem/images/SolLiqGas.jpg Check for number of particles being constant. Label melting, freezing, evaporation, sublimation, condensation.
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What is internal energy?
The energy of the particles in a material is called 'internal energy'.
The energy of the particles in a material is called 'internal energy'.
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What type of energy do particles gain when they are heated?
Particles gain kinetic (movement) energy when they are heated.
When particles are given heat energy they move faster, this because they gain kinetic (movement) energy.
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How does the internal energy of a material change as state changes?
A change of state from solid to liquid, liquid to gas or solid to gas requires an increase of the internal energy of the material.
A change of state from solid to liquid, liquid to gas or solid to gas requires an increase of the internal energy of the material.
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Why does the temperature of water not increase during melting and evaporation?
An increase of the internal energy of the material does not always result in a increase in temperature. Some energy is used in order to change state.
An increase of the internal energy of the material does not always result in a increase in temperature. Some energy is used in order to change state.
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What are there more of, chemicals or elements?
There are more chemicals than elements.
There are millions of chemicals in the world.
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What experiments did John Dalton carry out?
John Dalton did experiments to break down chemicals until they could not be split any further.
During the 1800s, John Dalton did experiments to break down chemicals until they could not be split any further.
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What are chemicals that can not be split into other chemicals called?
Chemicals that do not split into other chemicals are known as elements.
Dalton found some chemicals do not split into other chemicals, these are known as elements.
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What is an element made of?
An element is made of only one type of particle.
Elements are made of only one type of particle.
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What determines the element?
The type of particle determines the element. Each element has a unique number of protons.
The type of particle determines the element (chemical).
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What are chemicals called that are made of more than one element chemically bonded together?
Chemicals made of more than element chemically bonded are known as compounds.
Dalton found some chemical do split into other chemicals, these are known as compounds.
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What is a compound made up of?
Compounds are made up of more than one type of particle.
Compounds are made up of more than one type of particles.
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What did Dalton find out when he split compounds?
Dalton found compounds always split into the same proportions.
Dalton found compounds always split into the same proportions.
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How many elements are there and where can we find this list?
There are only around 100 types of atoms (elements) to make up the millions of chemicals.
There are only around 100 types of atoms (elements) to make up the millions of chemicals.
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What is an atom?
Atom is the smallest part of an element.
Atoms are the smallest part of a chemical, and can not be split chemically.
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What is a molecule?
Molecules are atoms that are bonded together.
Groups of bonded atoms are called Molecules.
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What is an element?
A chemical made up of only one type of atom.
Elements are made up of only one type of atom.
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What is a compound?
Compounds are made up of more than one type of atom, in a fixed combination.
Compounds are made up of more than one type of atom, in a fixed combination.
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What is a mixture?
A Mixture is a collection of different particles in the same place.
A Mixture is a collection of different particles in the same place.
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How do we represent chemicals universally?
chemical symbols and formulae for elements and compounds
Each element has a chemical symbol.
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What rules apply to all chemical symbols?
Some chemical symbols consist of two letters (as there are more than 26 elements). Chemical symbols start with a capital letter.
Some chemical symbols consist of two letters (as there are more than 26 elements). Chemical symbols start with a capital letter.
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What does the chemical formulae of a compound show?
Compounds have chemical formulae which show the elements in the compound.
Compounds have chemical formulae which show the elements in the compound.
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How can you tell a compound from the formula of it?
Compounds have chemical formulae with more than one capital letter in.
Compounds have chemical formulae with more than one capital letter in.
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How can you tell an element from the formula of it?
Elements have chemical formulae with only one capital letter in.
Elements have chemical formulae with only one capital letter in.
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How can we identify the number of elements in a compound?
We identify the number of elements in a compound by counting the number capital letters in the formulae.
Students can identify the number of elements in a compound from its formulae.
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Identify the number of element and atoms in the following formulae: CO Co NaOH MgO MgSO4 CaCO3 CaCl What are the elements in the above formulae?
CO 2 atoms, 2 elements. NaOH 4 atoms, 3 elements. MgO 2 atoms, 2 elements. MgSO4 6 atoms, 3 elements. CaCO3 5 atoms, 3 elements. CaCl 2 atoms, two elements. CO2 carbon and oxygen. NaOH sodium, oxygen and hydrogen. MgO magnesium and oxygen. MgSO4 magnesium, sulfur and oxygen. CaCO3 calcium, carbon and oxygen. CaCl calcium and chlorine.
Students can identify the number of atoms in a compound from its formulae.
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How can you represent a mixture in writing?
Mixture formulae have a plus sign in.
Mixture 'formulae' have a plus sign in.
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What is the conservation of mass?
conservation of mass changes of state and chemical reactions
There is no change of mass during a change of state as no particles are destroyed. This is known as the conservation of mass.
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What happens to the mass of particles in a chemical reaction?
There is no change of mass during chemical reactions as no particles are destroyed. This is known as the conservation of mass.
There is no change of mass during chemical reactions as no particles are destroyed. This is known as the conservation of mass.
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What is a chemical reaction?
Chemical reactions result from the rearrangement of atoms
Chemical reactions result from the rearrangement of atoms
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What is Brownian motion?
Brownian motion in gases is the proof of particles too small to see. The random motion of the large particle can only be explained by smaller particles hitting it.
Brownian motion in gases is the proof of particles too small to see. The random motion of the large particle can only be explained by smaller particles hitting it.
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What is a 'pure substance'?
the concept of a pure substance
A pure substance contains only what it is labelled as. It is not contaminated with something unexpected eg food grade chemicals.
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What is a trace substance?
A trace substance is chemical found in very small amounts. These may make substances impure.
A trace substance is chemical found in very small amounts. These may make substances impure.
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How can we identify a pure substance from an impure?
the identification of pure substances
Pure substances can be identified by being unable to separate them.
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How can we separate salt from sand?
simple techniques for separating mixtures: filtration, evaporation, distillation and chromatography
To be able to describe simple techniques for separating mixtures: filtration, evaporation.
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What is filtration?
Filtration separates by size of particle, normally solid and liquid.
Filtration separates by size of particle, normally solid and liquid.
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What is a residue?
The solid left behind in the filter is called the residue.
The solid left behind in the filter is called the residue.
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What is a filtrate?
The liquid that has passed through the filter is called the filtrate.
The liquid that has passed through the filter is called the filtrate.
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What allows us to separate substances through evaporation?
Evaporation separates by differences in boiling point, collecting the substance with the higher point.
Evaporation separates by differences in boiling point, collecting the substance with the higher point.
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What is distillation?
To be able to describe simple techniques for separating mixtures: Distillation.
To be able to describe simple techniques for separating mixtures: Distillation.
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How does distillation work?
Distillation separates by differences in boiling point, collecting the substance with the lower point.
Distillation separates by differences in boiling point, collecting the substance with the lower point.
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What is chromatography?
To be able to describe simple techniques for separating mixtures: chromotography.
To be able to describe simple techniques for separating mixtures: chromotography.
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Why would we use chromatography to identify a type of sweet?
Chromatography can be used to separate mixtures of coloured compounds.
Chromatography can be used to separate mixtures of coloured compounds.
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What does soluble mean?
If a solid can dissolve in particular liquid then it is know as 'soluble'.
If a solid can dissolve in particular liquid then it is know as 'soluble'.
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What does insoluble mean?
If a solid cannot dissolve in particular liquid then it is know as 'insoluble'
If a solid cannot dissolve in particular liquid then it is know as 'insoluble'
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What is a solution?
Solutions are mixtures of solids and liquids, in which the solid breaks down and behaves like a liquid.
Solutions are mixtures of solids and liquids, in which the solid breaks down and behaves like a liquid.
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What is the solid that dissolves in a liquid called?
The solid added is called the solute.
The solid added is called the solute.
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What is the liquid a solid dissolves into called?
The liquid added is called the solvent.
The liquid added is called the solvent.
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What happens to the solute particles when they dissolve?
The large solute (solid) crystal break down into smaller molecules which fit between the particles of the solvent.
The large solute (solid) crystal break down into smaller molecules which fit between the particles of the solvent.
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How do the particles behave once they have dissolved?
The solid can now behave like a liquid as the small molecules can move relative to each other.
The solid can now behave like a liquid as the small molecules can move relative to each other.
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What does it mean when a solution is saturated?
A saturated solution is one that can not dissolve any more solute.
A saturated solution is one that can not dissolve any more solute.
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In terms of particles, why does a solution become saturated?
When all the gaps between particles are full, no more solute can be dissolved.
When all the gaps between particles are full, no more solute can be dissolved.
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Why does increasing the temperature increase the amount of solute that can dissolve?
Increasing the temperature of the solvent, increases the speed the particles collide, creating bigger gaps. This allows more solute to dissolve in the solvent.
Increasing the temperature of the solvent, increases the speed the particles collide, creating bigger gaps. This allows more solute to dissolve in the solvent.
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What is solubility?
Solubility is a measure of how much solute can be dissolved in a solvent.
Solubility is a measure of how much solute can be dissolved in a solvent.
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What is concentration?
Concentration is the number of a particular type of particle in a volume of space.
Concentration is the number of a particular type of particle in a volume of space.
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What is diffusion?
diffusion in liquids and gases driven by differences in concentration
Diffusion is the movement of a substance from a region of higher concentration to a region of lower concentration.
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What happens to the particles in a fluid?
diffusion in terms of the particle model
Particles in a fluid are always moving.
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Why do particles move from an area where there are more to where ther
Half of a large number is more than half of a smaller number. So more particles will travel from a larger number of particles (high concentration), than are replaced by the smaller number moving form the smaller number of particles (lower concentration).
Half of a large number is more than half of a smaller number. So more particles will travel from a larger number of particles (high concentration), than are replaced by the smaller number moving form the smaller number of particles (lower concentration).
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What is a physical change?
Physical changes are changes of state.
Physical changes are changes of state.
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What happens to the particles in a physical change?
the difference between chemical and physical changes
Physical changes occur when particles are rearranged, but not change themselves.
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When do chemical changes occur?
Chemical changes occur when the make up of individual particles change.
Chemical changes occur when the make up of individual particles change.
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What happens to the atoms in a chemical reaction?
chemical reactions as the rearrangement of atoms
Chemical reactions result from the rearrangement of atoms
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What happens to atoms in chemical reactions?
Chemical reactions result from the rearrangement of atoms
Chemical reactions result from the rearrangement of atoms
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What are reactants?
Chemicals that react are call Reactants.
Chemicals that react are call Reactants.
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What are products?
Chemicals that are produce are call Products.
Chemicals that are produce are call Products.
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What is the difference between a chemical and a physical change?
The difference between chemical and physical changes.
The difference between chemical and physical changes.
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What happens to atoms in chemical reactions
Chemical reactions result from the rearrangement of atoms
Chemical reactions result from the rearrangement of atoms
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What 4 things tell us a chemical reaction has occurred?
Learn the signs of chemical reactions: 1. Change of color 2. Formation of gas 3. Formation of precipitate 4. Change of temperature (energy released)
Learn the signs of chemical reactions: 1. Change of colour 2. Formation of gas 3. Formation of precipitate 4. Change of temperature (energy released)
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How do we know that there is conservation of mass in a chemical reaction?
There is a 'Conservation of mass' during chemical reactions as atoms are rearranged not destroyed.
There is a 'Conservation of mass' during chemical reactions as atoms are rearranged not destroyed.
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What is combustion?
Combustion is the chemical reaction of burning.
Combustion is the chemical reaction of burning.
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What are the products and reactants in combustion?
During combustion the fuel joins with oxygen.
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What is an oxidation reaction?
Combustion is an oxidation reaction.
Combustion is an oxidation reaction.
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What type of chemical reaction is rusting?
Rusting is another example of an oxidation reaction
Rusting is another example of an oxidation reaction
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What reaction causes metals to tarnish?
Tarnish of metals is oxidation.
Tarnish of metals is oxidation.
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What happens in an exothermic reaction?
Exothermic chemical reactions give out heat, warming the surroundings. They feel hot.
Exothermic chemical reactions give out heat, warming the surroundings. They feel hot.
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What happens in an endothermic reaction?
Endothermic chemical reactions take in heat, cooling the surroundings. They feel cold.
Endothermic chemical reactions take in heat, cooling the surroundings. They feel cold.
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What happens in a thermal decomposition?
In thermal decomposition reactions, large molecules break down into smaller molecules when heated.
In thermal decomposition reactions, large molecules break down into smaller molecules when heated.
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What happens in a displacement reaction?
In a displacement reaction, a more reactive chemical will take the place of less reactive chemical.
In a displacement reaction, a more reactive chemical will take the place of less reactive chemical.
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What is the name of a reaction between an acid and an alkali?
A neutralisation reaction.
defining acids and alkalis in terms of neutralisation reactions
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What do we use the pH scale for?
The pH scale is used for measuring acidity/alkalinity; and indicators
the pH scale for measuring acidity/alkalinity; and indicators
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What is a catalyst and what do they do in a reaction?
Catalysts speed up a reaction without being used up themselves.
Catalysts speed up a reaction without being used up themselves.
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Can earthquakes and volcanoes happen anywhere on the Earth?
Earthquakes and volcanic eruptions only happen in certain places on Earth.
Earthquakes and volcanic eruptions only happen in certain places on Earth.
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What are tectonic plates?
Tectonic plates are pieces that the Earth's crust and the upper part of the mantle are split into.
Tectonic plates are pieces that the Earth's crust is split into.
Tectonic plates are pieces that the upper part of the mantle is split into.
Tectonic plates are pieces that the Earth's crust and the whole mantle are split into.
The Earth's crust and the upper part of the mantle are cracked into a number of large pieces (tectonic plates).
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Which is the thinnest layer out of the crust, mantle, outer core and inner core?
The crust is relatively very thin.
The crust is relatively very thin.
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What 3 forms of evidence did Alfred Wegener base his theory of crustal movement on?
Alfred Wegener theory of crustal movement (continental drift) based on: - Matched coastlines of Africa and S.America, - Matched rock formations, - Common fossils.
Alfred Wegener observed - Matched coastlines of Africa and S.America, - Matched rock formations, - Common fossils.
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What was Alfred Wegener's explanation for the forms of evidence?
This could be explained if the continents drifted apart.
This could be explained if the continents drifted apart.
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Why was Alfred Wegener's theory of continental drift not generally accepted?
Alfred Wegener's theory of continental drift was not generally accepted for many years because he couldn't explain how it could happen.
Alfred Wegener's theory of continental drift was not generally accepted for many years because he had no evidence.
Alfred Wegener's theory of continental drift was not generally accepted for many years because he had little evidence.
Alfred Wegener's theory of continental drift was not generally accepted for many years because there is lots of evidence against it.
Alfred Wegener theory of crustal movement (continental drift) was not generally accepted for many years because he couldn't explain how it could happen. We now believe...
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What moves the tectonic plates?
The tectonic plates are moved by convection currents within the Earth’s mantle. The plates to move at relative speeds of a few centimetres per year.
The tectonic plates are moved by convection currents within the Earth’s mantle. The plates move at relative speeds of a few metres per year.
The tectonic plates are moved by ocean currents. The plates move at relative speeds of a few centimetres per year.
The tectonic plates are moved by convection currents in the atmosphere. The plates move at relative speeds of a few metres per year.
Convection currents within the Earth's mantle cause the plates.
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Where does the energy come from to cause the movement of the tectonic plates?
The heat energy from natural radioactive processes in the core causes the tectonic plates to move.
The heat energy from natural radioactive processes in the mantle causes the tectonic plates to move.
The heat energy from natural chemical processes in the core causes the tectonic plates to move.
The heat energy from natural chemical processes in the mantle causes the tectonic plates to move.
The heat energy drives convection currents in the mantle, through the changing density (particle movement) of the heated mantle.
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What creates the heat in the core?
The heat in the core is released by natural radioactive processes.
The heat in the core is released by natural radioactive processes.
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What is the energy transform occurring in the core?
Nuclear to Heat
Gravitational to Heat
Chemical to Heat
Elastic to Heat
Nuclear energy is transformed into heat energy.
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How fast do the plates move on average?
The plates move at relative speeds of a few centimetres per year.
The plates move at relative speeds of a few centimetres per year.
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What do the sudden movements of the tectonic plates cause?
The sudden movements of tectonic plates can cause both earthquakes and volcanic eruptions.
The sudden movements of tectonic plates can cause earthquakes only.
The sudden movements of tectonic plates can cause volcanic eruptions only.
The sudden movements of tectonic plates can cause earthquakes and tidal waves.
The movements can be sudden and disastrous. Earthquakes and / or volcanic eruptions occur at the boundaries between tectonic plates.
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Starting at the center, what are the layers that make up the Earth?
The Earth consists of a core, mantle and crust.
The Earth consists of a crust, mantle and core.
The Earth consists of a mantle, a core and crust.
The Earth consists of a mantle, crust and core.
The Earth consists of a core, mantle and crust, and is surrounded by the atmosphere.
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What are the relative sizes of the core and mantle in how much of the diameter of the Earth they take up?
The Core is about half the diameter of the Earth, with the Mantle making up the other half.
The Core is about half the diameter of the Earth, with the Mantle making up the other half.
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How are P and S waves used to discover what the inner Earth is like?
DESIRABLE: Our knowledge of the structure of the Earth comes mainly from studying how the shockwaves from earthquakes (seismic waves) travel through it. Earthquakes produce two types of waves that can travel through the Earth: - Longitudinal faster travelling Primary, P (pressure) waves, which move through liquids as well as solids; - Transverse slower travelling Secondary, S waves, which travel only through solids. The S-wave shadow is what give rise to the idea of a core. http://www.mrcorfe.com/KS4/Edexcel/Physics/P1-11-NowYouSeeIt/EarthStructure.php
DESIRABLE: Our knowledge of the structure of the Earth comes mainly from studying how the shockwaves from earthquakes (seismic waves) travel through it. Earthquakes produce two types of waves that can travel through the Earth: - Longitudinal faster travelling Primary, P (pressure) waves, which move through liquids as well as solids; - Transverse slower travelling Secondary, S waves, which travel only through solids. The S-wave shadow is what give rise to the idea of a core. http://www.mrcorfe.com/KS4/Edexcel/Physics/P1-11-NowYouSeeIt/EarthStructure.php
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What is the Earth mainly composed of?
The Earth is composed of mainly of: - iron - oxygen - silicon - magnesium
The Earth is composed of mainly of: - iron - oxygen - silicon - tungsten
The Earth is composed of mainly of: - iron - argon - silicon - magnesium
The Earth is composed of mainly of: - iron - argon - silicon - tungsten
The Earth is composed of mainly of: - iron (32.1%), - oxygen (30.1%), - silicon (15.1%), - magnesium (13.9%).
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What is the Earth's core mainly composed of?
The Earth's core is composed of mainly of iron with smaller amounts of nickel.
The Earth's core is composed of mainly of nickel with smaller amounts of iron.
The Earth's core is composed of mainly of oxygen with smaller amounts of nitrogen.
The Earth's core is composed of mainly of nitrogen with smaller amounts of oxygen.
The Earth's core is composed of mainly of iron (88.8%) with smaller amounts of nickel (5.8%).
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What is the Earth's crust mainly made up of?
The Earth's crust is composed of mainly of oxygen, chemically locked up in rocks.
The Earth's crust is composed of mainly of iron,
The Earth's crust is composed of mainly of nickle,
The Earth's crust is composed of mainly of nitrogen,
The Earth's crust is composed of mainly of oxygen (47%), chemically locked up in rocks. The most common of which are Silica, Silicon Dioxide (54%) and Alumina, Aluminum oxide (16%). - Something to do with revising Elements and compounds.
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What type of chemical is the air?
The atmosphere is composed of mainly nitrogen and oxygen with small proportions of various other gases.
The atmosphere is composed of mainly nitrogen and oxygen.
The atmosphere is composed of mainly iron and nickle.
The atmosphere is composed of mainly iron and nickle with small proportions of various gases.
The air in the atmosphere is a mixture.
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What is the atmosphere composed of?
The atmosphere is composed of: - about four-fifths nitrogen (80%) - about one-fifth oxygen (20%) - small proportions of various other gases, including carbon dioxide, water vapour and noble gases.
The atmosphere is composed of: - about four-fifths nitrogen (80%) - about one-fifth oxygen (20%) - small proportions of various other gases, including carbon dioxide, water vapour and noble gases.
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What is the test for oxygen gas?
The gas test for oxygen is it relights a glowing spill.
The gas test for oxygen is it turns lime water cloudy.
The gas test for oxygen is it makes a squeaky pop when lit.
The gas test for oxygen is it puts out a burning spill.
The gas test for oxygen is it relights a glowing spill.
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What is the test for carbon dioxide?
The gas test for carbon dioxide is it turns lime water cloudy.
The gas test for carbon dioxide is it relights a glowing spill.
The gas test for carbon dioxide is it makes a squeaky pop when lit.
The gas test for carbon dioxide is it puts out a burning spill.
The gas test for carbon dioxide is it turns lime water cloudy.
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What is the test for hydrogen gas?
The gas test for hydrogen is it makes a squeaky pop when lit.
The gas test for hydrogen is it relights a glowing spill.
The gas test for hydrogen is it turns lime water cloudy.
The gas test for carbon dioxide is it puts out a burning spill.
The gas test for hydrogen is it makes a squeaky pop when lit.
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What process maintains the levels of oxygen and carbon dioxide in the atmosphere?
The levels in the atmosphere are maintained by photosynthesis.
The levels in the atmosphere are maintained by combustion.
The levels in the atmosphere are maintained by decomposition.
The levels in the atmosphere are maintained by evaporation.
The oxygen and carbon dioxide levels in the atmosphere are maintained by photosynthetic organisms, such as plants and algae.
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Why is photosynthesis important?
the dependence of almost all life on Earth on the ability of photosynthetic organisms, such as plants and algae, to use sunlight in photosynthesis to build organic molecules that are an essential energy store and to maintain levels of oxygen and carbon dioxide in the atmosphere - Energy transfer from sun to plant, chloroplast transform atoms rearranged (conserved in reaction). Oxygen we need for respiration = glucose.
Photosynthetic organisms, such as plants and algae, use sunlight in photosynthesis to build organic molecules that are an essential energy store.
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Why is oxygen important in the atmosphere?
Oxygen is need for respiration which releases energy from glucose. This is essential for all life. Therefore all life depends on the energy from the sun and the photosynthetic
Oxygen is need for respiration which releases energy from glucose. This is essential for all life. Therefore all life depends on the energy from the sun and the photosynthetic
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Which gas is used as a sign of life on other planets?
Oxygen is a sign that life is on an other planet.
Nitrogen is a sign that life is on an other planet.
Carbon dioxide is a sign that life is on an other planet.
Methane is a sign that life is on an other planet.
In the search for life on other planets, looking for oxygen is a sign that life is on the planet.
0
What are the different physical and chemical properties that can vary?
the varying physical and chemical properties of different elements - Melting points. - Boiling points. - Densities. - Hardness. - Reactivity.
the varying physical and chemical properties of different elements - Melting points. - Boiling points. - Densities. - Hardness. - Reactivity.
0
How did Mendeleev decide where to put things in the periodic table?
That repeating properties were used to form the groups in the Mendeleev periodic table.
That repeating properties were used to form the groups in the Mendeleev periodic table.
0
How does the reactivity change as you go down Group one?
The reactivity of elements increases as group one is descended in the periodic table.
The reactivity of elements increases as group one is descended in the periodic table.
0
How does the reactivity of group 7 elements change as you ascend the group?
The reactivity of elements increases as group seven is ascended in the periodic table.
The reactivity of elements increases as group seven is ascended in the periodic table.
0
How reactive are group zero elements?
Group zero do not react.
Group zero do not react.
0
How does the placement of elements on the periodic table affect its properties?
The closer elements are to each other on the periodic table, the more likely they are to react in a similar way.
The closer elements are to each other on the periodic table, the more likely they are to react in a similar way.
0
What are the rows in the periodic table called?
The rows in the periodic table are called periods.
The rows in the periodic table are called periods.
0
What are the columns in the periodic table called?
The columns in the periodic table are called groups
The columns in the periodic table are called groups
0
Where can metals be found in the periodic table?
Metals are found to the lower left on the periodic table.
Metals are found to the lower left on the periodic table.
0
Where can non-metals be found in the periodic table?
Nonmetals are found to the upper right on the periodic table.
Nonmetals are found to the upper right on the periodic table.
0
What is the most abundant type of element on the periodic table?
Metals make up the majority of the elements on the periodic table.
Metals make up the majority of the elements on the periodic table.
0
What are the properties of metals?
The properties of metals include: - Lustrous (shiny) - Sonorous (makes a ringing sound) - Hard. - High density (are heavy for their size) - High tensile strength (resist being stretched) - High melting and boiling points. - Good conductors of heat and electricity.
The properties of metals include: - Lustrous (shiny) - Sonorous (makes a ringing sound) - Hard. - High density (are heavy for their size) - High tensile strength (resist being stretched) - High melting and boiling points. - Good conductors of heat and electricity.
0
What are the properties of non-metals?
The properties of non-metals include: - Low melting and boiling points. - Insulators of
The properties of non-metals include: - Low melting and boiling points. - Insulators of
0
What are the products when you react an acid with a metal?
reactions of acids with metals to produce a salt plus hydrogen
reactions of acids with metals to produce a salt plus hydrogen
0
What are the products when you react an acid with an alkali?
reactions of acids with alkalis to produce a salt plus water
reactions of acids with alkalis to produce a salt plus water
0
What is formed when metal oxides dissolve?
Metal oxides dissolve to form alkali solutions.
Metal oxides dissolve to form alkali solutions.
0
What is formed when non-metal oxides dissolve?
Non-metal oxides dissolve to form acid solutions.
Non-metal oxides dissolve to form acid solutions.
0
How can we identify types of oxides?
Identify types of oxides by testing pH
Identify types of oxides by testing pH
0
When Iron Sulfide mixes with Lead Nitrate, what happens?
There is a reaction; Lead Sulfide and Iron Nitrate are produced.
Predict the outcome of reactions with metals and metal salt solutions given the reactivity series.
0
What happens in a displacement reaction?
In displacement reactions the more reactive metal displaces (takes the place) of the less reactive metal.
In displacement reactions the more reactive metal displaces (takes the place) of the less reactive metal.
0
What is definition of a rate?
A rate is how quickly something happens / how much in a bit of time.
Metals will react with acid at different rates.
0
What gas is produced when a metal reacts with an acid?
When Metals react with acid with they produce (a salt and) hydrogen gas.
When Metals react with acid with they produce (a salt and) hydrogen gas.
0
What do all acids contain?
Acids contain hydrogen (ions) particles.
Acids contain hydrogen (ions) particles.
0
What is the reactivity series?
An order of metals based on their reactivity (how quickly / strongly they react).
Metals can be put into order of reactivity called the 'the reactivity series'
0
Other than a gas, what is produced when an acid reacts with a metal?
When Metals react with acid with they produce a salt (and hydrogen gas).
When Metals react with acid with they produce a salt (and hydrogen gas).
0
Draw particle diagrams for a metal reacting with an acid.
- Three different types of particle. Before: - Metal particle by itself - Hydrogen particle with another particle After: - Metal with other particle - Hydrogen paricle by itself. - Hydrogen in pairs
Draw particle diagrams for metals reacting with acid.
0
Write a word equation for metals reacting with acid.
Format: Metal Acid -> Salt Hydrogen Where the salt has Metal name and then the non metal ion from the acid. eg Iron Hydrochloric acid -> Iron Chloride Hydrogen Gas
Write word equations for metals reacting with acid.
0
Write a symbol equation for metals reacting with acid.
eg Fe HCl -> FeCl H Balanced equations for bonus mark. Correct formula second bonus mark
Write symbol equations for metals reacting with acid.
0
Which two non-metal elements are often added to the reactivity series?
Carbon and Hydrogen are often be added to the reactivity series.
Carbon and Hydrogen are often added to the reactivity series for comparison.
0
Why don't we find pure metals that are more reactive than hydrogen in the ground?
The metal displaces the hydrogen, found in ground water, to produce metal oxides.
Metals more reactive than hydrogen will react with water as they will displace the hydrogen forming metal oxides.
0
What do we call rocks that have significant amounts of metal compounds in?
The rocks that have significant amounts of metal oxides in are known as ores.
The rocks that have significant amounts of metal oxides in are known as ores.
0
What needs to be done to get useable metals?
Metal in metal oxides needs to be chemical separated from the oxygen.
In order to obtain useable metal it needs to be chemically separated from the oxygen.
0
What type of furnace is used to produce iron?
The blast furnace is used to produce Iron from iron oxide.
The blast furnace is used to obtaining some metals from metal oxides using carbon. eg Iron from iron oxide.
0
What is added to to the furnace to remove the oxygen from the ore?
Carbon is added to blast furnace remove the oxygen from the ore.
Carbon is more reactive than iron so the carbon displaces the iron to form carbon dioxide leaving the iron by itself.
0
What determines if carbon can displace the metal?
Carbon can only displace metals that are less reactive than itself.
Carbon can only displace metals that are less reactive than itself.
0
Draw a labelled diagram to show how to collect gas over water.
- Up turned measuring cylinder / test tube - In tub of water - Delivery tube from reaction to under measuring cylinder - Reaction in a conical flask.
Gas can be collected over water using a delivery tube.
0
What is a better method to measure the amount of gas produced by a reaction?
A better method to measure the volume of gas produced by a reaction is to use a gas syringe.
Gas can be collected using a gas syringe. This is an improved method to measure the volume of gas.
0
How are ceramic objects made?
Ceramic materials are solids made by baking a starting material in a very hot oven or kiln.
Ceramic materials are solids made by baking a starting material like clay, in a very hot oven or kiln.
0
Give two examples of a ceramic material.
Ceramic materials include: Pottery; Bricks; Glass; Cement; Diamond
Ceramic materials include: Pottery; Bricks; Glass; Cement; Diamond
0
Ceramic materials are hard,what does this mean?
Ceramic materials are hard, because they are not easy to scratch /
Ceramic materials are hard, so not easy to scratch.
0
How are ceramics used to be at their strongest?
Ceramic materials are strong under compression (being squashed).
Ceramic materials are strong under compression.
0
Ceramics are brittle. What does this mean?
Ceramics are brittle, because they can not absorb energy quickly or bend without breaking
Ceramics are brittle.
0
How are metals used to be at their strongest?
Metals are in tension (being stretched).
Metals have a high Tensile Strength
0
Metals are Sonorous. What does this mean?
Metals are Sonorous because they make a ringing sound when struck.
Metals are Sonorous
0
Metals are malleable. What does this mean?
Metals are malleable because they can be hammered into shape.
Metals are malleable
0
Metals are ductile. What does this mean?
Metals are ductile because they can be drawn (stretched) into a tread.
Metals are ductile
0
Metals are lustrous. What does this mean?
Metals are lustrous because they are shiny.
Metals are lustrous
0
Metals are good conductor. What does this mean?
Metals are good conductor because they allow the flow of heat and/or electricity through it.
Metals are good conductors of heat and electricity.
0
What are the general properties of ceramics?
Ceramics have High melting points (so they're heat resistant). Great hardness and strength, Considerable durability (they're long-lasting and hard-wearing) and Low electrical and thermal conductivity (they're good insulators).
These are the general properties of ceramics and metals, but there are exceptions.
0
What is the chemistry name for plastics?
Plastics are polymers.
Plastics are polymers.
0
What determines how a polymer is used?
The properties of the polymer determine how they are used.
There are many different polymers. Their properties determine how they are used.
0
Name four properties of some polymers.
Polymers can be flexible, cheap, electrical insulator, strong, tough resistant to chemicals and generally have a low density.
Polymers can be flexible, cheap, electrical insulator, strong, tough resistant to chemicals and generally have a low density.
0
What is a composite material?
Composites are made up of more than type of material.
Composites are made up of more than type of material.
0
Why are composites used?
Composites have a mixture of properties from the materials that make them up.
Composites have a mixture of properties from the materials that make them up.
0
Explain why reinforced concrete used for bridges?
MARK USING SCIENCE EXPLANATION LADDER
Reinforced concrete is a composite of concrete (ceramic) and metal bars.
0
What are glass Reinforced Plastics?
Glass Reinforced Plastics (GRP) are a composite of glass fibres (ceramic) and a plastic (polymer).
Glass Reinforced Plastics (GRP) are a composite of glass fibres (ceramic) and a plastic (polymer).
0
How are particles in a solid arranged?
Particels in a solid are tightly packed, usually in a regular pattern.
Particles in a solid are arranged in a lattice (pattern).
0
Do all solids have the particles arranged in the same pattern?
No, different types of solids have their particles arranged in a differnet shaped lattices (patterns).
Different types of solid are have their particles arranged in a differnet shaped lattices (patterns).
0
Why are metals malleable and ductile?
Metals are malleable and ductile because their particles are arranged in layers with weak bonds between them.
Metals are malleable and ductile because their particles are arranged in layers with weakish bonds between them. (This is an oversimplification as dislocations and grain boundaries are the true weaknesses)
0
What happens to the metals layers when a force is applied?
When a force is applied to the metal layers they slide over each other changing the material's shape.
When a force is applied to the metal layers they slide over each other changing the material's shape.
0
Why are metals known as tough?
Metals are tough because when there is a shock of energy, it can be absorbed in the flexibility of these weak bonds.
Metals are tough because when there is a shock of energy, it can be absorbed in the flexibility of these weak bonds.
0
Why are ceramics brittle?
Ceramics are brittle because when there is a shock of energy, it can not be absorbed as there is no flexibility in the strong bonds.
Ceramics are brittle because when there is a shock of energy, it can not be absorbed as there is no flexibility in the strong bonds.
0
Why are ceramics hard and brittle?
Ceramics are hard and brittle because their particles are held in a lattice shape such as a tetrahedral.
Ceramics are hard and brittle because their particles are held in a lattice shape such as a tetrahedral.
0
Why are tetrahedrals strong shapes?
Tetrahedrals are strong shapes as each particle is held in place by triangles of bonds.
Tetrahedrals are strong shapes as each particle is held in place by triangles of bonds.
0
What does a strong structure mean?
The strong structure means that particles will not move as much as others so can scratch the softer material. But it also means that a shock of energy can not be absorbed by the bonds as there is no flexibility in the structure.
The strong structure means that particles will not move as much as others so can scratch the softer material. But it also means that a shock of energy can not be absorbed by the bonds as there is no flexibility in the structure.
0
How are particels in a polymer arranged?
The particles in polymers are a arranged in chains.
The particles in polymers are a arranged in chains.
0
What are the bonds in a polymer like?
The bonds in the chain are very strong, but the force between chains are relatively weak.
The bonds in the chain are very strong, but the force between chains are relatively weak.
0
What does the length of a polymer chain affect?
The length of the particle chain affects how the chains interact with each other and so the properties of the polymer.
The length of the particle chain affects how the chains interact with each other and so the properties of the polymer.
0
What are the applications of ceramics, polymers and composites?
Ceramics are used in bricks and pottery. Polymers are used in PVC, Lycra,Nylon and polyethene. Composites: waterproof clothing eg; Gore Tex Car wheels.
Application of ceramics, polymers and composites (qualitative)
0
Are all rocks the same age?
There are lots of different rocks of all sorts of ages.
There are lots of different rocks of all sorts of ages.
0
Where are the oldest rocks found?
The oldest rocks are found in Africa, Canada and Australia.
The oldest rocks are found in Africa, Canada and Australia.
0
Where are the youngest rocks on the earth generally found?
The youngest rocks are found around volcanoes.
The youngest rocks are found around volcanoes.
0
Why has the amount of rock material on the earth remained fairly constant since its formation?
No new material gained or lost from the planet (with the exception of the small number of meteorites that have collided with the planet)
There has been no new rock material added to the earth since it was created apart from a small amount of meteorites.
0
What materials are new rocks made from?
Those recycled by the earth over its existence.
New rocks are made from recycled material.
0
What type of rocks are formed when molten rock freezes?
Igneous rocks
Igneous rocks are formed when molten rocks freeze.
0
Describe the structure of particles in an igneous rock
Particles in an igneous rock are fixed in a lattice, the reason why the rocks hold their shape.
When frozen, the particles in the rocks are fixed in a lattice, that is why the rocks hold their shape.
0
Solids are made up of crystals. What are crystals?
Crystals are regions of a single lattice orientation.
Solids are made up of crystals. Crystals are regions of a single lattice orientation.
0
How does the rate at which something freezes affect the size of the crystals it contains?
The slower the rate of freezing, the greater the size of the crystals that are formed within that structure.
When solids freeze quickly the crystals are small.
0
Why are the crystals formed larger when an object freezes more slowly?
The crystals are large because the particles have more time to line up before freezing.
The crystals are large because the particles have more time to line up before freezing.
0
Why are the crystals formed smaller when an object freezes quickly?
The crystals are small because the particles have less time to line up before freezing.
The crystals are small because the particles have less time to line up before freezing.
0
What size crystals are formed when solids freeze slowly?
When solids freeze slowly the crystals are large.
When solids freeze slowly the crystals are large.
0
What is the impact on the structure of an igneous rock when it forms slowly under the ground?
Due to it cooling slowly, it will contain large crystals.
When igneous rocks are formed under the ground they cool slowly so the crystals are large.
0
What is the impact on the structure of an igneous rock when it forms above the ground or in water, resulting in tit cooling rapidly?
Due to it cooling quickly, it will contain small crystals.
When igneous rocks are formed above ground or in water they cool quickly so the crystals are small.
0
Does the size of crystals affect the properties of a rock?
The size of crystals affects some of the properties of the rock.
The size of crystals affects some of the properties of the rock.
0
What is weathering?
Weathering is breaking up of rock where it stands.
Weathering is breaking up of rock where it stands.
0
Over time, what happens to rocks as they are weathered?
Rocks are broken down into increasing smaller particles
Rocks are broken down into increasing smaller particles: Gravel; Sand; Silt; Clay
0
What is chemical weathering?
Chemical weathering is the weathering of rocks caused by chemicals. For example, rainwater is naturally slightly acidic because carbon dioxide from the air dissolves in it. Minerals in rocks may react with the rainwater, causing the rock to be weathered.
Weathering can be chemical weathering, in which rocks are broken down when the particles that make them up are changed.
0
What is physical weathering?
Physical weathering of rocks occurs when they are broken down, but the particles that make them up are not chemically changed.
Weathering can be physical weathering, in which rocks are broken down when the particles that make them up are not changed. But the forces between the particles are overcome to separate them into small pieces of rock.
0
How are sedimentary rocks formed?
Sedimentary rocks are formed when sediment (little pieces of weathered rock) is laid down in layers under water and then compressed by layers above. The water between the sediment is squeezed out and the sediment bonds together.
Sedimentary rocks are formed when sediment (little pieces of weathered rock) is laid down in layers under water and then compressed by layers above. The water between the sediment is squeezed out and the sediment bonds together.
0
What may occur when organisms fall into the sediment of a forming rock?
If organisms fall into the sediment then the rock can take the shape of the organism. These formations are fossils.
If organisms fall into the sediment then the rock can take the shape of the organism. These formations are fossils.
0
What causes the formation of a metamorphic rock?
Metamorphic rocks are formed when either igneous or sedimentary rocks are heated and under great pressure.
Metamorphic rocks are formed when either igneous or sedimentary rocks are heated under great pressure.
0
Where are the resources we rely upon extracted from?
All resources we use come from come from the Earth's crust or the atmosphere.
All resources come form come from the Earth's crust or the atmosphere.
0
Why is coal a better source of energy than wood?
Coal contains more energy per kilogram than wood as it is a concentrated form of wood without moisture in.
Coal contains more energy per kilogram than wood as it is a concentrated form of wood without moisture in.
0
How is crude oil formed?
Crude oil (and natural gas) is formed when sea creatures (mainly microscopic) are compressed under layers of sediment
Crude oil (and natural gas) is formed when sea creatures (mainly microscopic) are compressed under layers of sediment.
0
How is coal formed?
Coal is a sedimentary rock formed when trees and plants are compressed under layers of sediment. (The highest grade coal, Anthracite, is actually metamorphic)
Coal is a sedimentary rock formed when trees and plants are compressed under layers of sediment. (The highest grade coal, Anthracite, is actually metamorphic)
0
What uses do we have for crude oil?
Crude oil can be processed into fuels, chemicals and plastics.
Crude oil can be processed into fuels, chemicals and plastics.
0
How are most metals obtained from the Earth's crust?
Most metals are dug up from the earths crust in the form of ores.
Metals are dug up from the earth in the form of ores.
0
What is a ceramic material?
Ceramics are made from muds, dug up from the Earth's crust.
Ceramics are made from muds that are dug up from the earth
0
What is it important that we recycle?
Resources on the Earth are limited, It's important that the way we behave now does not make life difficult or impossible for future generations.
the efficacy of recycling
0
What are the impacts on the Earth of increasing the amount of carbon dioxide in the Earth's atmosphere?
The result of increasing carbon dioxide in the Earth's atmosphere will lead to global warming (increase of the Earth's average surface temperature). This will lead to changes in weather patterns, causing drought in some places and flooding in others. Also polar ice caps will melt, raising sea levels and causing increased coastal erosion and flooding of low-lying land, including land where major cities lie.
the production of carbon dioxide by human activity and the impact on climate
0
The emissions of which gases result in the formation of acid rain?
Acid rain is most caused by emissions of sulfur dioxide and nitrogen oxide
ENQUIRY: Planning Aim: To find out how the concentration of acid (rain) affects the rate of reaction with marble chips
0
How can you test for the presence of carbon dioxide gas?
Bubble the gas through limewater. If carbon dioxide is present then it will turn cloudy.
The test for carbon dioxide is to bubble the gas through lime water. If it turns cloudy this is a positive result.
0
Are the Earth's resources infinite?
The Earth's resources are not infinite, they are limited.
Earth as a source of limited resources
0
Mod
Number of Questions
0S
10
1B
10
1C
10
1P
10
BI
5
C1
C1.1
Atomic Structure
C1.2
The Periodic Table
C1.3
Bonding and structure of substances
C1.4
Properties of substances
C1.5
Use of amount of substance in relation to volumes of gases
C1.6
Test Title
C2
C2.1
Rates of reaction
C2.2
Crude Oil, Hydrocarbons and Cracking
C2.3
Analytical chemistry
C2.4
Evolution of the atmosphere
C2.5
Sustainable development
C2.6
Synthetic and Natural Polymers (Separates only)
1C
1C.01
1C.02
1C.03
1C.04
1C.05
1C.06
1C.07
1C.08
1C.09
1C.10
1C.12
2C
2C.1
Atoms, Molecules; Elements, Compounds & Mixtures
2C.2
Enquiry
2C.3
Halfway Review
2C.4
Particles in action
2C.5
Assessment
3C
3C.1
Substances and Separation
3C.2
Enquiry
3C.3
Halfway Review
3C.4
Mixtures
3C.5
Assessment
4C
4C.1
Chemical & Physical Changes
4C.2
Enquiry
4C.3
Halfway Review
4C.4
Catalysts
4C.5
Assessment
5C
5C.1
Structure of the Earth
5C.2
Enquiry
5C.3
Halfway Review
5C.4
Atmosphere
5C.5
Assessment
6C
6C.1
More Chemical reactions
7C
7C.1
Reactivity and Rocks
7C.2
Enquiry
7C.3
Halfway Review
7C.4
Material Science
7C.5
Assessment
8C
8C.1
The Rock Cycle
8C.3
Halfway Review
8C.4
Using Earth's Resources
8C.5
Assessment
1
B1
C1
P1
2
B2
C2
P2
B
1B
2B
3B
4B
5B
6B
8B
C
1C
2C
3C
4C
5C
6C
7C
8C
l
Del
I
BI
P
1P
2P
3P
4P
5P
6P
7P
8P
S
0S
