Year 12 foundation
Practise Boltzmann graphs
Maxwell–Boltzmann distributions
Interpret distribution curves, temperature changes, activation energy and catalysts.
Kinetics
Work from collision theory and Maxwell–Boltzmann curves into experimental rate equations, rate constants and Arrhenius plots. Choose the bit that is costing you marks.
Pick the evidence you need to practise
Year 13
Practise rate equations
Rate equations
Use initial-rate tables to find orders, write the rate equation, and calculate k with its units.
Year 13
Deduce the orders
Rate Order Detective
Deduce orders from mixed evidence rather than relying on a neat one-variable table.
Year 13
Practise Arrhenius
Arrhenius equation & plots
Calculate with k = Ae^(−Ea/RT), read ln k against 1/T plots, and diagnose the usual graph and unit traps.
Practical skills
Practise rates experiments
Rates practical questions
Initial rates, continuous monitoring, graph gradients, variables and activation-energy experiments.
Link the topic together
Use one generated mini-paper to move from experimental rate evidence into k, Arrhenius calculations and the particle explanation behind the temperature effect.
If you are not sure where to start
- Read the rate evidence.Find the individual orders before worrying about k.
- Write the rate equation.The experimental orders determine the concentration terms and the units of k.
- Connect k to temperature.Use Arrhenius when the question gives k at different temperatures or asks about an ln k against 1/T plot.
- Explain the chemistry.Use Maxwell–Boltzmann ideas to explain why temperature changes k and why a catalyst changes Ea instead.
Where AQA and OCR A differ
- Maxwell–Boltzmann distributions, collision theory and temperature effects form the Year 12 foundation.
- Rate equations use orders 0, 1 and 2; students deduce orders from experimental evidence and connect them to the rate-determining step.
- Arrhenius calculations use k = Ae^(−Ea/RT). The linear plot is ln k against 1/T with gradient −Ea/R.
- AQA gives the required Arrhenius equations and R when needed.
- Maxwell–Boltzmann distributions, activation energy, catalysts and temperature effects support later rate-equation work.
- Rate equations are derived from initial-rate, continuous-monitoring and other experimental evidence; OCR can also use constant half-life as first-order evidence.
- The Arrhenius plot is ln k against 1/T. OCR requires graphical determination of Ea and the pre-exponential factor A.
- For A, the intercept means the value of ln k at 1/T = 0; it is not simply the visible left edge of a truncated graph.