Schemes of Work

C1
- C1.7
  - Lesson 01 - What energy changes happen during reactions? Lesson Plan Lesson Title
    - 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.
      - Suggested Activity:
        Investigating the energy change of reactions
        Equipment Required:
        Collins C5.1
        polystyrene cups lids
        thermometers
        250ml beakers, spatulas
        25ml cylinders
        zinc powder 1M copper sulphate sol
        magnesium powder 1M sulfuric acid
        Citric acid crystals 1M sodium hydrogen carbonate soln
        Sodium carbonate powder 1M ethanoic acid.
        DEMO
        10g ammonium chloride
        20g Barium hydroxide
        Piece of thin wood
        water dispenser
        datalogger temp probe
    - If a reaction transfers energy to the surroundings the product molecules must have less energy than the reactants, by the amount transferred.
    - An exothermic reaction is one that transfers energy to the surroundings so the temperature of the surroundings increases.
    - Exothermic reactions include combustion, many oxidation reactions and neutralisation.
    - Everyday uses of exothermic reactions include self-heating cans and hand warmers.
    - An endothermic reaction is one that takes in energy from the surroundings so the temperature of the surroundings decreases.
    - Endothermic reactions include thermal decompositions and the reaction of citric acid and sodium hydrogencarbonate. Some sports injury packs are based on endothermic reactions.
    - Some sports injury packs are based on endothermic reactions.
    - Students should be able to distinguish between exothermic and endothermic reactions on the basis of the temperature change of the surroundings
    - Students should be able to evaluate uses and applications of exothermic and endothermic reactions given appropriate information.
    - Limited to measurement of temperature change. Calculation of energy changes or ?H is not required.
  - Lesson 02 - What is a reaction pathway? Lesson Plan Lesson Title
    - Chemical reactions can occur only when reacting particles collide with each other and with sufficient energy.
      - Suggested Activity:
        Plan Required Practical for Energy Changes
        Equipment Required:
        Practical planning sheets
        Temperature changes required practical
    - The minimum amount of energy that particles must have to react is called the activation energy.
    - 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.
    - 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
    - Students should be able to use reaction profiles to identify reactions as exothermic or endothermic
    - Students should be able to explain that the activation energy is the energy needed for a reaction to occur.
    - 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.
    - The energy needed to break bonds and the energy released when bonds are formed can be calculated from bond energies.
    - 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.
    - In an exothermic reaction, the energy released from forming new bonds is greater than the energy needed to break existing bonds.
    - In an endothermic reaction, the energy needed to break existing bonds is greater than the energy released from forming new bonds.
    - Students should be able to calculate the energy transferred in chemical reactions using bond energies supplied.
  - Lesson 03 - Required Practical - Temperature change in a reaction Lesson Plan Lesson Title
    - Required practical 4 - temperature change in reactions (AT skills 1,3,5,6)
  - Lesson 04 - How are batteries and fuel cells able to store energy? Lesson Plan Lesson Title
    - Cells contain chemicals which react to produce electricity.
    - The voltage produced by a cell is dependent upon a number of factors including the type of electrode and electrolyte.
    - A simple cell can be made by connecting two different metals in contact with an electrolyte.
    - Batteries consist of two or more cells connected together in series to provide a greater voltage.
    - In non-rechargeable cells and batteries the chemical reactions stop when one of the reactants has been used up. Alkaline batteries are non-rechargeable.
      - Suggested Activity:
        Students handle hydrogen powered cars
        Equipment Required:
        hydrogen powered cars - charged up!
    - Rechargeable cells and batteries can be recharged because the chemical reactions are reversed when an external electrical current is supplied.
    - Students should be able to interpret data for relative reactivity of different metals and evaluate the use of cells.
    - Students do not need to know details of cells and batteries other than those specified.
    - 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.
    - The overall reaction in a hydrogen fuel cell involves the oxidation of hydrogen to produce water.
    - Hydrogen fuel cells offer a potential alternative to rechargeable cells and batteries.
    - Students should be able to evaluate the use of hydrogen fuel cells in comparison with rechargeable cells and batteries
    - Students should be able to write the half equations for the electrode reactions in the hydrogen fuel cell. (HT only)
  - Lesson 05 - How does electrolysis split compounds? Lesson Plan Lesson Title
    - 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.
    - (HT only) Write balanced half equations and ionic equations where appropriate.
    - 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.
      - Suggested Activity:
        Class practical:
        electrolysis of copper sulfate
        Equipment Required:
        Beaker 250ml
        Graphite electrodes
        wooden separators
        DC power supply (6 volt)
        Light bulb 6 volt
        Leads croc/plug
        1M copper sulphate soln
    - (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)
    - 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.
    - Students should be able to predict the products of the electrolysis of binary ionic compounds in the molten state.
    - (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)
    - During electrolysis, at the cathode (negative electrode), positively charged ions gain electrons and so the reactions are reductions.
    - At the anode (positive electrode), negatively charged ions lose electrons and so the reactions are oxidation reactions.
    - Reactions at electrodes can be represented by half equations, for example:
      2H 2e- ? H2
      and
      4OH- ? O2 2H2O 4e-
      or
      4OH- 4e- ? O 2H2O
  - Lesson 06 - How are metals like aluminium extracted from their ores? Lesson Plan Lesson Title
    - 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.
      - Suggested Activity:
        Demo:
        electrolysis of molten lead bromide
        http://www.rsc.org/learn-chemistry/resource/res00001725/electrolysing-molten-lead-ii-bromide?cmpid=CMP00005239
        Equipment Required:
        Access to a fume cupboard DEMO,
        Lead bromide
        Bunsen burner
        tripod
        gauze
        THINGS BELOW IN BRACKETS ARE IN CHEMICAL CUPBOARD IN TRAY L
        (Porcelain crucible,
        2x
        Graphite rod electrodes, about 15 cm long,
        Rubber bung with two holes about 1 cm apart to fit the graphite rods)
        DC power supply 12 V
        Ammeter, 0-5 A, ideally a large
        demonstration model
        Leads croc/plugs x2
    - Large amounts of energy are used in the extraction process to melt the compounds and to produce the electrical current.
    - Aluminium is manufactured by the electrolysis of a molten mixture of aluminium oxide and cryolite using carbon as the positive electrode (anode).
    - Students should be able to explain why a mixture is used as the electrolyte
    - Students should be able to explain why the positive electrode must be continually replaced.
    - (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)
  - Lesson 07 - What products will be created at the electrodes during electrolysis? Lesson Plan Lesson Title
    - The ions discharged when an aqueous solution is electrolysed using inert electrodes depend on the relative reactivity of the elements involved.
    - At the negative electrode (cathode), hydrogen is produced if the metal is more reactive than hydrogen.
    - At the positive electrode (anode), oxygen is produced unless the solution contains halide ions when the halogen is produced.
    - This happens because in the aqueous solution water molecules break down producing hydrogen ions and hydroxide ions that are discharged.
      - Suggested Activity:
        Demo:
        Rainbow electrolysis
        http://www.rsc.org/learn-chemistry/resource/res00000735/colourful-electrolysis?cmpid=CMP00004981
        Equipment Required:
        U-shaped tube
        Clamp and clamp stand
        Carbon electrodes 2
        Plug/croc leads
        Power pack (low voltage, d.c.)
        Beaker (100 cm3)
        salty water
        Universal indicator soln
    - Students should be able to predict the products of the electrolysis of aqueous solutions containing a single ionic compound.
      - Suggested Activity:
        Class:
        Electrolysis of NaCl to identify unexpected products
        Equipment Required:
        Clamp and clamp stand
        Carbon electrodes and electrode holders, 2 of each (Note 3)
        Electrical leads, 2
        Power pack (low voltage, d.c.)
        Beaker (100 cm3)
        Spatula
        Stirring rod
        NaCl solution
    - (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)
  - Lesson 08 - Required practical 3 - Electrolysis Lesson Plan Lesson Title
    - Required practical 3 - electrolysis (developing hypothesis) (AT skills 3,7,8)
      - Suggested Activity:
        RP Electrolysis plan and carry out
        Equipment Required:
        RP 3 Electrolysis
        0.5M copper sulphate soln
        0.5M sodium chloride soln
        0.5M copper chloride soln
        0.5M sodium sulphate soln
        carbon electrodes holders
        beakers
        power packs
        plug/croc leads
        Blue litmus paper
        forceps
        MAYBE SET UP 4 OF EACH CHEM READY IN BEAKERS WITH ELECTRODES(rather than 60 beakers)