Explain why increasing the temperature increases the rate of reaction between two reactants.

OCR GCSE Chemistry A: Gateway Science (J248) — C5.1 Monitoring chemical reactions · Explain · 4 marks · View as Markdown

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

A student is investigating how changing the temperature affects how quickly a chemical reaction produces a gas. She notices that when she heats the reactants, the gas is produced much more quickly.

Model answer (4 marks)

Increasing the temperature gives the particles more kinetic energy, so they move faster.

As a result, the particles collide more often.

A greater proportion of the collisions have energy equal to or greater than the activation energy.

Thus there are more successful collisions, so the rate of reaction increases.

Examiner tips

Use the term "activation energy" and "successful collisions". Show the chain: temperature → kinetic energy → collision frequency → energy distribution → reaction rate. Keep answer concise and to the points.

Common mistakes

Confusing temperature with pressure. Failing to mention activation energy or successful collisions. Writing in a narrative style instead of bullet points.

Mark scheme (4 marks)

Increasing temperature gives particles more kinetic energy / particles move faster
Particles collide more often / more frequent collisions
A greater proportion of particles have energy equal to or greater than the activation energy
There are more successful collisions, so the rate of reaction increases

Key terms in this question

rate of reaction