# Neutralisation is an exothermic reaction. When dilute hydrochloric acid is added to sodium hydroxide solution, the temperature of the mixture rises. Explain, in terms of bond breaking and bond forming, why the temperature of the mixture increases during this neutralisation reaction.

> Edexcel GCSE Chemistry (1CH0) — 7.2 Heat energy changes in chemical reactions · Explain · 4 marks

## Mark scheme (4 marks)

1. Energy is required / 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 new bonds is greater than the energy needed to break existing bonds
4. This surplus / excess energy is transferred to the surroundings, causing the temperature to increase

## Key terms

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

## Related

- [Revision notes for Edexcel GCSE Chemistry (1CH0)](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/neutralisation-is-an-exothermic-reaction-when-40328550) · Published by Druglandscape Ltd.