Skip to content

6. The rate and extent of chemical change

Rates of reaction

4 lessons
6.1 Measuring the rate of reaction How to measure the rate of a reaction from the amount of reactant used or product formed over time, using gas volume, loss of mass or a colour change, how to calculate a mean rate, and (Higher) how to find the rate at a moment from the gradient of a tangent. AQA Edexcel OCR 6.2 Collision theory and factors affecting rate Collision theory: reactions happen when particles collide with at least the activation energy. How concentration, pressure, surface area and temperature change the frequency and energy of collisions, and so the rate. AQA Edexcel OCR 6.3 Catalysts What catalysts are, how they increase the rate of reaction by providing a pathway with a lower activation energy, how to show this on a reaction profile, how to identify a catalyst, and enzymes as biological catalysts. AQA Edexcel OCR 6.4 Required practical: rates of reaction The required practical on how concentration affects the rate of reaction: the disappearing cross method with sodium thiosulfate and acid, the gas collection method with marble chips or magnesium, variables, calculating 1/time, and improving accuracy. AQA Edexcel OCR

Reversible reactions and equilibrium

3 lessons
6.5 Reversible reactions What reversible reactions are and the ⇌ symbol, how changing conditions changes the direction of a reaction (ammonium chloride, hydrated copper sulfate), and why the energy transferred is the same in each direction but exothermic one way and endothermic the other. AQA Edexcel OCR 6.6 Dynamic equilibrium What dynamic equilibrium is: in a closed system, the forward and reverse reactions keep happening at the same rate, so the amounts of reactants and products stay constant, though not equal. AQA Edexcel OCR 6.7 Changing conditions: Le Chatelier's principle Le Chatelier's principle: how changing concentration, temperature and pressure moves the position of equilibrium, how to predict the effect on the yield, why a catalyst does not change the position, and the Haber process as an example. Higher only AQA Edexcel OCR