# A student investigates the energy change when zinc powder is added to copper sulfate solution. The temperature of the mixture rises. Explain why the temperature rises and describe how the student could use the results to compare this reaction with a different displacement reaction.

> AQA A-Level Chemistry (7405) — 3.1.4 Energetics · Explain and Describe · 5 marks

> Zinc is more reactive than copper. When zinc powder is added to copper sulfate solution, zinc displaces copper and the temperature of the mixture increases.

## Mark scheme (5 marks)

1. The reaction is exothermic
2. Energy is released when new bonds are formed (in the products) / the energy released forming bonds in the products is greater than the energy taken in breaking bonds in the reactants
3. The temperature rise (ΔT) is measured by subtracting the initial temperature from the highest temperature reached
4. Use the same volume / mass of copper sulfate solution and the same mass of zinc (i.e. keep quantities the same / control variables) so that comparisons are valid
5. The reaction with the greater temperature rise is more exothermic / releases more energy

## Key terms

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

## Related

- [Revision notes for AQA A-Level Chemistry (7405)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain and Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-investigates-the-energy-change-e4b4bdc7) · Published by Druglandscape Ltd.