4th Sep '25

Schemes of Work

C2
- C2.1
  - Lesson 01 - How can we measure the rate of a chemical reaction? Lesson Plan Lesson Title
    - 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
      - Suggested Activity:
        Demo - iodine clock reaction with 5 student helpers
        time how long to react.
        sketch/plot a graph of results to work out rate from graph or calculate direct from results
        Equipment Required:
        RSC iodine clock demo (in your chem book)
    - The quantity of reactant or product can be measured by the mass in grams or by a volume in cm3.
      - Suggested Activity:
        Focus on gas collection (RP skills)
        
        React CaCO3 with dilute HCl and measure the volume of CO2 evolved against time. IV - number of marble chips or volume of acid.
        
        Calculate rate by mass of chips / time taken or volume or gas / time taken.
        
        Record the results and plot a graph of results of volume of gas against time.
        Equipment Required:
        Class set
        Marble Chips
        2M, 1.5M, 1M, 0.5M, 0.25M HCl
        Conical flasks
        Gas syringes
        Balances
        Sieve
    - The units of rate of reaction may be given as g/s or cm3/s.
      - Suggested Activity:
        Explain what is meant by the units:
        • g/s
        • cm3/s
        • 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)
      - Suggested Activity:
        Extended writing: write instructions to another student how to calculate the mean rate of reaction.
    - 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
    - Students should be able to draw, and interpret, graphs showing the quantity of product formed or quantity of reactant used up against time
      - Suggested Activity:
        Analyse graphical data on ppt to identify and explain
        ie:
        •initially rate is fast
        •slows down
        •reaction completion
        
        Go further: complete the measuring rate of reaction worksheet.
    - 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
    - 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.
      - Suggested Activity:
        Get students to calculate the gradient from graphs they have analysed using tangents.
  - Lesson 02 - How do temperature and pressure affect the rate of a chemical reaction? Lesson Plan Lesson Title
    - 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.
      - Suggested Activity:
        use the fluffy balls to represent particles in reactions with changing factors. e.g higher/lower concentrations
        Equipment Required:
        fluffy balls
    - The minimum amount of energy that particles must have to react is called the activation energy.
    - 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.
      - Suggested Activity:
        Circus of mini practicals measuring the rate of reaction. Students record their results in the table (shared area).
        
        Go further: In terms of rates of reaction explain why grass needs to be cut more often in the summer months. You should include any relevant chemical equations.
        Equipment Required:
        Station 1: marble chips and acid, conical flask with gas syringe, different concentration of HCl, small measuring cylinders.
        jewellery balance
        sieve
        
        Station 2: marble chips and acid with delivery tube water bath set up, varying particle size of marble chips, measuring cylinders.
        jewellery balances
        sieve
        
        Station 3: mini scale sodium thiosulfate reaction with different temperature reactant (room temp, ice and water bath), measuring cylinders.
        
        Station 4: pieces of magnesium, 1 M hydrochloric acid, conical flask and gas syringe, measuring cylinders.
    - 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.
    - Students should be able to recall how changing the pressure of reacting gases affects the rate of chemical reactions.
    - Students should be able to recall how changing the temperature affects the rate of chemical reactions.
  - Lesson 03 - How do surface area and concentration affect the rate of a chemical reaction? Lesson Plan Lesson Title
    - 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
      - Suggested Activity:
        Investigate particle size impact on rate of reaction. Collecting gas using water troughs. Calculate rate using 1 / time taken.
        Equipment Required:
        3cm magnesium ribbon pieces
        Mg powder
        1M hcl
        conical flasks
        delivery tubes
        troughs
        measuring cylinders
        stopclocks
        spatulas
    - Increasing the concentration increases the frequency of collisions and makes the collisions and so increases the rate of reaction.
    - Students should be able to recall how changing the concentrations of reactants in solution affects the rate of chemical reactions.
      - Suggested Activity:
        Go further: create summary diagrams to explain these effects without using any words.
    - 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.
    - 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.
      - Suggested Activity:
        Extended writing: Use collision theory to explain the change in rate of reaction in terms of particle behaviour for:
        
        • Concentration
        • Pressure
        • Surface area
        • Temperature
        • Catalyst.
    - 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
    - Students should be able to recall how changing the surface area of solid reactants affects the rate of chemical reactions.
  - Lesson 04 - Why are catalysts often used in chemical reactions? Lesson Plan Lesson Title
    - Catalysts change the rate of chemical reactions but are not used up during the reaction. Different reactions need different catalysts.
      - Suggested Activity:
        demo:
        Elephants toothpaste
        Equipment Required:
        elephants toothpaste in large measuring cylinder and tray
    - Enzymes act as catalysts in biological systems.
      - Suggested Activity:
        Find out which is the best catalyst at decomposing hydrogen peroxide
        Equipment Required:
        per group:
        75 cm3 of 10 volume hydrogen peroxide solution. - About 0.5 g of powdered manganese(IV) oxide (manganese dioxide, MnO2). - About 0.5 g of lead(IV) oxide (lead dioxide, PbO2). - About 0.5 g of iron(III) oxide (red iron oxide, Fe2O3). - A small piece (about 1 cm3) of potato. - A small piece (about 1 cm3) of liver.
        washing up liquid in small beaker with pipette
        stop clock
        50ml cylinders
    - 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.
    - A reaction profile for a catalysed reaction can be drawn in the following form: (energy level diagram with reduced Ea with catalyst)
      - Suggested Activity:
        Students draw their predicted reaction profiles for with and without a catalyst -> evaluate and correct.
    - 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.
    - Students should be able to explain catalytic action in terms of activation energy.
    - Students do not need to know the names of catalysts other than those specified in the subject content.
      - Suggested Activity:
        Why are catalysts used in industry?
        
        Go further: You are in charge of a factory producing a chemical. Which factor would you change to increase the rate of reaction? Why?
    - Students should be able to recall how the presence of a catalyst affects the rate of chemical reactions.
  - Lesson 05 - What are reversible reactions? Lesson Plan Lesson Title
    - Students should be able to plan, complete and analyse a practical to measure how changing the concentration affects the rate of reaction.
      - Suggested Activity:
        Required practical 5:
        Investigate how changes in concentration affect the rates of reactions by a method involving measuring the volume of a gas produced and a method involving a change in colour or turbidity. Calculate rate using 1 / time taken.
        Equipment Required:
        Class set:
        
        Magnesium ribbon cut to 1cm in length.
        2M, 1.5M, 1.0M, 1.5M, 0.5M, 0.25M hydrochloric acid
        Conical flasks
        Gas syringes
        Stopclocks
        50ml measuring cylinders
    - Required practical 5 - rates of reaction (developing a hypothesis) (AT skills 1,3,5,6)
  - Lesson 06 - What is dynamic equilibrium? Lesson Plan Lesson Title
    - In some chemical reactions, the products of the reaction can react to produce the original reactants.
      - Suggested Activity:
        Show the reversible reaction symbol - what does this mean?
    - Such reactions are called reversible reactions and are represented: A B (reversible arrow) C D
    - For example: ammonium chloride (heat - reversible arrow - cool) ammonia hydrogen chloride.
      - Suggested Activity:
        Demo 1:
        ammonium chloride is a white solid that breaks down into ammonia and hydrogen
        chloride gases when heated, leave to cool to see reverse reaction.
        Equipment Required:
        demo 1:
        ammonium chloride in boiling tube with mineral wool in the top
    - If a reversible reaction is exothermic in one direction, it is endothermic in the opposite direction.
      - Suggested Activity:
        Demo 2:
        heat hydrous copper sulfate and then leave to cool/add water to show reverse reaction.
        Equipment Required:
        Demo 2:
        boiling tube of hydrous copper sulfate, distilled water.
    - 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.
      - Suggested Activity:
        Show energy change sketch graphs for exothermic and endothermic reactions to help explain.
    - The direction of reversible reactions can be changed by changing the conditions.
      - Suggested Activity:
        Give several examples of reactions and ask students what will happen when temperature, concentration and pressure are changed.
        
        Go further: Students are to write their own exam question based on the learning in the topic. Must include a mark scheme on the other side. Swap with another student -> answer -> hand back and peer assess.
  - Lesson 07 - How can equilibrium be affected? Lesson Plan Lesson Title
    - 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.
      - Suggested Activity:
        Demo 1:
        The equilibrium of the cobalt chloride–water system;
        temperature. Observe colour of reaction at different temperatures (20,30,40 degrees)
        Equipment Required:
        class practical: -TECH notes- see chemistry folder C6.10 to make up solutions of coblat (II) chloride solutions.
        three test tubes labelled A, B and C each set to "turn" at the required temperatures for each group of students.
        water baths set up at 20, 30 and 40 degrees.
    - 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.
      - Suggested Activity:
        demo of co
    - Students should be able to interpret appropriate given data to predict the effect of a change in temperature on given reactions at equilibrium.
    - 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.
      - Suggested Activity:
        Watch https://www.youtube.com/watch?v=dUMmoPdwBy4
    - 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.
    - Students should be able to interpret appropriate given data to predict the effect of pressure changes on given reactions at equilibrium.
      - Suggested Activity:
        Go Further: complete the Haber process worksheet.
    - The relative amounts of all the reactants and products at equilibrium depend on the conditions of the reaction.
      - Suggested Activity:
        Ask students what happens when a bottle of coke is opened -> bubbles fizz out -> why? Affect of pressure on carbonic acid reversible reactions.
    - If a system is at equilibrium and a change is made to any of the conditions, then the system responds to counteract the change.
      - Suggested Activity:
        Watch the two videos and annotate the snap shots (hand outs - video 1 and video 2 in shared folder):
        
        https://www.youtube.com/watch?v=7zuUV455zFs
        
        https://www.youtube.com/watch?v=XhQ02egUs5Y
        
        Go further: Write the correct sentences for the sentence exerts (shared area).
    - The effects of changing conditions on a system at equilibrium can be predicted using Le Chatelier's Principle.
    - Students should be able to make qualitative predictions about the effect of changes on systems at equilibrium when given appropriate information.
      - Suggested Activity:
        Complete dynamic equilibrium worksheet.
    - 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 a reactant is increased, more products will be formed until equilibrium is reached again.
    - If the concentration of a product is decreased, more reactants will react until equilibrium is reached again.
    - 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.
  - Lesson 08 - What is the Haber Process? Lesson Plan Lesson Title
    - The Haber process is used to manufacture ammonia, which can be
      used to produce nitrogen-based fertilisers.
    - Some of the hydrogen and nitrogen reacts to form
      ammonia.
    - The reaction is reversible so some of the ammonia
      produced breaks down into nitrogen and hydrogen: nitrogen hydrogen --> <-- ammonia
    - ? 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
    - On cooling, the ammonia liquefies and is removed. The remaining
      hydrogen and nitrogen are recycled.
    - MS 1a
      Recognise and use
      expressions in decimal form.
      MS 1c
      Use ratios, fractions and
      percentages.
    - ? apply the principles of dynamic equilibrium in
      Reversible reactions and dynamic equilibrium to the Haber process
    - ? explain the trade-off between rate of production and position of equilibrium
    - The raw materials for the Haber process are nitrogen and hydrogen
    - Students should be able to recall a source for the nitrogen and a source for the hydrogen used in the Haber process
    - The purified gases are passed over a catalyst of iron at a high
      temperature (about 450?C) and a high pressure (about 200
      atmospheres).