# A student uses a cold pack to reduce swelling after a sports injury. When the cold pack is activated, the contents dissolve in water and the pack becomes noticeably cold. Explain why the pack becomes cold, using your knowledge of endothermic reactions and bond breaking and bond making.

> OCR GCSE Chemistry A: Gateway Science (J248) — C3.3 Types of chemical reactions · Explain · 4 marks

> Cold packs are used by sports teams to treat minor injuries on the pitch. When activated, the pack rapidly drops in temperature without any external cooling source.

## Mark scheme (4 marks)

1. The reaction taking place is endothermic
2. Energy is taken in from the surroundings (the pack / skin)
3. More energy is required to break bonds in the reactants than is released when bonds are formed in the products
4. This causes the temperature of the surroundings to decrease, making the pack feel cold

## Key terms

- [endothermic reaction](https://www.gradenine.co.uk/glossary/endothermic-reaction)
- [bond breaking](https://www.gradenine.co.uk/glossary/bond-breaking)
- [bond making](https://www.gradenine.co.uk/glossary/bond-making)

## Related

- [Revision notes for OCR GCSE Chemistry A: Gateway Science (J248)](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/a-student-uses-a-cold-pack-92634514) · Published by Druglandscape Ltd.