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3 Physical chemistry

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  1. (a) Energetics

    1. Know that chemical reactions in which heat energy is given out are described as exothermic, and those in which heat energy is taken in are described as endothermic

    2. Describe simple calorimetry experiments for reactions such as combustion, displacement, dissolving and neutralisation

    3. Calculate the heat energy change from a measured temperature change using the expression Q = mcΔT

    4. Calculate the molar enthalpy change (ΔH) from the heat energy change, Q

    5. Draw and explain energy level diagrams to represent exothermic and endothermic reactions

    6. Know that bond-breaking is an endothermic process and that bond-making is an exothermic process

    7. Use bond energies to calculate the enthalpy change during a chemical reaction

    8. Practical: investigate temperature changes accompanying some of the following types of change: • salts dissolving in water • neutralisation reactions • displacement reactions • combustion reactions.

  2. (b) Rates of reaction

    1. 3.9Experiments on factors affecting reaction rate

      Describe experiments to investigate the effects of changes in surface area of a solid, concentration of a solution, temperature and the use of a catalyst on the rate of a reaction

    2. 3.10Effects of factors on reaction rate

      Describe the effects of changes in surface area of a solid, concentration of a solution, pressure of a gas, temperature and the use of a catalyst on the rate of a reaction

    3. 3.11Collision theory and reaction rate

      Explain the effects of changes in surface area of a solid, concentration of a solution, pressure of a gas and temperature on the rate of a reaction in terms of particle collision theory

    4. 3.12Catalyst definition

      Know that a catalyst is a substance that increases the rate of a reaction, but is chemically unchanged at the end of the reaction

    5. 3.13Catalysts and activation energy

      Know that a catalyst works by providing an alternative pathway with lower activation energy

    6. 3.14CReaction profile diagrams

      Draw and explain reaction profile diagrams showing ΔH and activation energy

    7. 3.15Surface area and concentration rate practical

      Practical: investigate the effect of changing the surface area of marble chips and of changing the concentration of hydrochloric acid on the rate of reaction between marble chips and dilute hydrochloric acid

    8. 3.16Catalytic decomposition practical

      Practical: investigate the effect of different solids on the catalytic decomposition of hydrogen peroxide solution

  3. (c) Reversible reactions and equilibria

    1. Know that some reactions are reversible and this is indicated by the symbol ⇌ in equations

    2. Describe reversible reactions such as the dehydration of hydrated copper(II) sulfate and the effect of heat on ammonium chloride

    3. Know that a reversible reaction can reach dynamic equilibrium in a sealed container

    4. Know that the characteristics of a reaction at dynamic equilibrium are: • the forward and reverse reactions occur at the same rate • the concentrations of reactants and products remain constant.

    5. Understand why a catalyst does not affect the position of equilibrium in a reversible reaction

    6. Know the effect of changing either temperature or pressure on the position of equilibrium in a reversible reaction: • an increase (or decrease) in temperature shifts the position of equilibrium in the direction of the endothermic (or exothermic) reaction • an increase (or decrease) in pressure shifts the position of equilibrium in the direction that produces fewer (or more) moles of gas References to Le Chatelier's principle are not required