# A student dissolves citric acid powder in water to make a lemon-flavoured drink. The student notices that the outside of the glass feels noticeably cooler after mixing. Explain why the glass feels cooler, using your knowledge of bond breaking and bond making.

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

> When citric acid dissolves and reacts in water, an overall energy change occurs between the student's hand and the glass.

## Mark scheme (4 marks)

1. The reaction is endothermic
2. Energy is taken in from the surroundings (the glass / the student's hand)
3. More energy is required to break bonds in the reactants than is released when bonds form in the products
4. Because the surroundings lose energy, the temperature of the surroundings (the glass) decreases

## Key terms

- [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-dissolves-citric-acid-powder-8bc8315c) · Published by Druglandscape Ltd.