# A student dissolves ammonium nitrate crystals in water in a beaker. The outside of the beaker feels noticeably colder after mixing. Explain what type of energy change is occurring and why the beaker feels cold.

> OCR GCSE Chemistry A: Gateway Science (J248) — C3.1 Introducing chemical reactions · Explain · 4 marks

> Ammonium nitrate is used in instant cold packs for treating sports injuries. When ammonium nitrate dissolves in water, an energy change occurs.

## Mark scheme (4 marks)

1. The reaction/process is endothermic
2. Energy is taken in from the surroundings
3. The surroundings (beaker/water) lose energy / the temperature of the surroundings decreases
4. More energy is required to break bonds in the reactants than is released when bonds form in the products / overall energy change is positive

## 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)
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