# Combustion is an example of an exothermic reaction. Explain, in terms of bond breaking and bond forming, why the overall energy change for a combustion reaction is exothermic.

> Eduqas GCSE Chemistry — C5 Energy changes · Explain · 4 marks

## Mark scheme (4 marks)

1. Energy must be supplied / is taken in to break bonds in the reactants
2. Energy is released when new bonds are formed in the products
3. The energy released from forming bonds is greater than the energy needed to break bonds
4. Therefore the overall energy change transfers energy to the surroundings, so the temperature of the surroundings increases

## Key terms

- [exothermic reaction](https://www.gradenine.co.uk/glossary/exothermic-reaction)
- [bond breaking](https://www.gradenine.co.uk/glossary/bond-breaking)
- [bond forming](https://www.gradenine.co.uk/glossary/bond-forming)
- [overall energy change](https://www.gradenine.co.uk/glossary/overall-energy-change)

## Related

- [Revision notes for Eduqas GCSE Chemistry](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/combustion-is-an-example-of-an-3d6ffe8b) · Published by Druglandscape Ltd.