# Cold packs used in sports medicine contain ammonium nitrate and water in separate compartments. When the pack is squeezed, the compartments break and the ammonium nitrate dissolves, causing the pack to feel cold. Explain, in terms of energy and bond breaking and bond making, why the pack feels cold, and describe what a reaction profile for this type of reaction would look like compared to one for an exothermic reaction.

> OCR A-Level Chemistry B: Salters (H433) — 3.2 Physical chemistry · Explain · 5 marks

> Cold packs used in sports medicine contain ammonium nitrate and water in separate compartments. When the pack is squeezed, the compartments break and the ammonium nitrate dissolves, causing the pack to feel cold.

## Mark scheme (5 marks)

1. The reaction/dissolving process is endothermic
2. Energy is taken in from the surroundings, causing the temperature of the surroundings to decrease
3. More energy is required to break bonds in the reactants than is released when bonds are formed in the products
4. On the reaction profile, the products are at a higher energy level than the reactants
5. This is the opposite of an exothermic reaction profile, where the products are at a lower energy level than the reactants

## Key terms

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

## Related

- [Revision notes for OCR A-Level Chemistry B: Salters (H433)](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/cold-packs-used-in-sports-medicine-28606ccd) · Published by Druglandscape Ltd.