Explain why increasing the temperature of a reaction mixture increases the rate of reaction.

Pearson Edexcel International GCSE Chemistry (4CH1) — 3.2 Rates of reaction · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

A student notices that a chemical reaction proceeds noticeably faster when the reaction mixture is heated from 20 °C to 40 °C.

Model answer (4 marks)

Particles have more kinetic energy at higher temperature.
Particles collide more frequently.
A greater proportion of particles have energy equal to or greater than the activation energy.
There are therefore more successful collisions per unit time, so the rate of reaction increases.

Examiner tips

  • Use the four points in order, matching the mark scheme. Show the link between temperature, kinetic energy, collision frequency and activation energy. Keep sentences short and use exam‑specific terminology.
  • common_mistakes
  • :
  • Failing to mention the activation energy. Using vague phrases like "more energy" without linking to collision frequency. Mixing up the order of the points or omitting one of the four key ideas.

Mark scheme (4 marks)

  1. Particles have more kinetic energy (at higher temperature)
  2. Particles collide more frequently / often
  3. A greater proportion of particles have energy equal to or greater than the activation energy
  4. There are therefore more successful collisions per unit time, so the rate of reaction increases

Key terms in this question

rate of reaction

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