# Hand warmers contain chemicals that react when the pack is activated. Explain why a hand warmer feels warm to the touch, and describe what happens to the temperature of the surroundings during this type of reaction.

> OCR GCSE Chemistry A: Gateway Science (J248) — C3.2 Energetics · Explain · 4 marks

> A student activates a disposable hand warmer and notices it quickly becomes hot. She also observes that when she dissolves ammonium nitrate in water to make a cold pack, the outside of the container feels cold.

## Mark scheme (4 marks)

1. The hand warmer undergoes an exothermic reaction
2. Energy is transferred to the surroundings (from the reaction)
3. The temperature of the surroundings increases (in an exothermic reaction)
4. The cold pack reaction is endothermic because energy is taken in from the surroundings, so the temperature of the surroundings decreases

## Key terms

- [surroundings](https://www.gradenine.co.uk/glossary/surroundings)

## 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/hand-warmers-contain-chemicals-that-react-857d2128) · Published by Druglandscape Ltd.