Effect of Temperature on Rate

This lesson covers how changing the temperature affects the rate of reaction using collision theory, as required by the Edexcel GCSE Combined Science specification (1SC0). Temperature is arguably the most important factor — it affects both the frequency and the energy of collisions.

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The Key Idea

When the temperature is increased:

1. Particles gain more kinetic energy and move faster.
2. Collisions happen more frequently (particles meet each other more often).
3. A greater proportion of collisions have energy equal to or above the activation energy (Eₐ).
4. Therefore there are more successful collisions per second and the rate increases.

Exam Tip: This is one of the most commonly asked 4–6 mark questions. You must give both reasons: (1) more frequent collisions AND (2) a greater proportion of particles have energy ≥ Eₐ. Giving only one reason limits you to a maximum of half the marks.

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Collision Theory Explanation in Detail

Reason 1: More Frequent Collisions