Exothermic vs Endothermic: what's the difference?
GCSE Chemistry
Two types of energy change in a reaction — whether energy is given out to, or taken in from, the surroundings.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Exothermic vs Endothermic — side by side
| Exothermic | Endothermic | |
|---|---|---|
| Energy | Released to the surroundings | Taken in from the surroundings |
| Temperature of surroundings | Increases (feels hot) | Decreases (feels cold) |
| Energy of products | Lower than reactants | Higher than reactants |
| Examples | Combustion, neutralisation, most oxidation | Thermal decomposition, photosynthesis, some dissolving |
Exam tip — how to tell them apart: EXOthermic = energy EXits (temperature rises). Endothermic takes energy in (temperature falls).
Common trap: On an energy profile, exothermic products sit BELOW reactants; endothermic products sit above.
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