This how it works covers How Each Factor Links to Collision Theory within Factors Affecting Rate for GCSE Chemistry. Revise Factors Affecting Rate in Rates of Reaction for GCSE Chemistry with 24 exam-style questions and 18 flashcards. This topic shows up very often in GCSE exams, so students should be able to explain it clearly, not just recognise the term. It is section 5 of 13 in this topic. Use this how it works to connect the idea to the wider topic before moving on to questions and flashcards.
⚙️ How Each Factor Links to Collision Theory
Every factor that affects rate must be explained using collision theory. Here is the precise mechanism for each one:
- Temperature: Higher temperature → particles have more kinetic energy → move faster → collide more frequently AND a greater proportion of particles now have energy ≥ Ea → more successful collisions per second → faster rate.
- Concentration (or pressure for gases): More particles in the same volume → particles are closer together → collisions are more frequent → more successful collisions per second → faster rate. (Energy of particles does not change.)
- Surface area: Breaking a solid into smaller pieces exposes more particles at the surface → more particles are available to collide with the other reactant → more collisions and more successful collisions per second → faster rate. (Energy and concentration don't change.)
- Catalyst: Provides an alternative reaction pathway with a lower activation energy → a greater proportion of the existing collisions now have energy ≥ the new, lower Ea → more successful collisions per second → faster rate. Crucially, a catalyst is not consumed — it can catalyse the reaction again and again.
Practice questions for Factors Affecting Rate
Which of the following factors does NOT affect the rate of a chemical reaction?
Explain, in terms of particles, why increasing temperature increases the rate of reaction.