Explain the difference between an exothermic reaction and an endothermic reaction, and give one example of each type of reaction.

Cambridge International IGCSE Chemistry (0620) — 5.1 Exothermic and endothermic reactions · Explain · 4 marks · View as Markdown

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

Model answer (4 marks)

In an exothermic reaction energy is released to the surroundings.
In an endothermic reaction energy is absorbed from the surroundings.
Example of an exothermic reaction: combustion of methane.
Example of an endothermic reaction: photosynthesis.

Examiner tips

Use the word ‘released’ for exothermic and ‘absorbed’ for endothermic. Give one clear example for each type. Keep the answer short and to the point.

Common mistakes

Confusing the direction of energy flow. Giving the same example for both reactions. Using vague terms like ‘heat’ without specifying release or absorption.

Mark scheme (4 marks)

In an exothermic reaction, energy is transferred/released to the surroundings
In an endothermic reaction, energy is absorbed/taken in from the surroundings
A correct example of an exothermic reaction
A correct example of an endothermic reaction

Key terms in this question

exothermic reaction · endothermic reaction