Unit Overview
Reaction kinetics (AS)
CIE A-Level ChemistryΒ· 5 min read π n/a
1. Unit at a glance
The topics in this unit build logically from foundational measurement to explanatory models and real-world application. We start with how to measure and calculate reaction rate, then use collision theory to explain why different factors change reaction speed, before finally applying this model to understand how catalysts work.
Explore the 3 interconnected sub-topics below:
Rates of reaction
Learn how to define, measure, and calculate reaction rate from experimental data.
β β± 10 min
Collision theory
Use the collision theory model to explain how common factors alter reaction rate.
β β β± 12 min
Catalysis
Explore how catalysts lower activation energy and classify homogeneous/heterogeneous catalysis.
β β β β± 15 min
2. Common Pitfalls
Wrong move:
Confusing reaction rate with reaction extent/yield
Why:
Rate measures how quickly a reaction proceeds, not how much product forms when it finishes.
Correct move:
Remember a fast reaction can have low yield, and a slow reaction can go to completion.
Wrong move:
Forgetting that catalysts are chemically unchanged at the end of a reaction
Why:
Catalysts take part in the reaction but are regenerated, so they do not get used up.
Correct move:
Always recall catalysts are regenerated, only change the reaction pathway, not the overall enthalpy change.
3. Quick Reference Cheatsheet
Concept | Key Definition/Fact |
|---|---|
Rate of reaction | Change in concentration of reactant/product per unit time: |
Activation energy () | Minimum energy colliding particles must have to undergo a successful reaction |
Effect of temperature increase | Increases the proportion of particles with energy β₯ , raising the frequency of successful collisions |
Homogeneous catalyst | Catalyst that is in the same physical state as the reactants |
Heterogeneous catalyst | Catalyst that is in a different physical state to the reactants |
What's Next
Begin your study of this unit with the first sub-topic, which covers the core definitions and calculations you will need for all subsequent kinetics work. After you complete all sub-topics in this unit, move on to the next unit on chemical equilibrium, which explores how far reactions proceed, complementing what you learned about how fast they go here.