# Describe what happens to the internal energy of a substance as it melts, and explain why its temperature does not change during melting.

> AQA GCSE Physics (8463) — 4.3.1 Changes of state and the particle model · Describe and Explain · 4 marks

> A student heats a block of wax until it completely melts. The student notices that the temperature stays the same while the wax is melting, even though energy is being continuously supplied.

## Mark scheme (4 marks)

1. The internal energy of the substance increases during melting.
2. The energy supplied increases the potential energy of the particles (not the kinetic energy).
3. Temperature is related to the average kinetic energy of the particles.
4. Since the kinetic energy of the particles does not increase, the temperature does not change / remains constant.

## Key terms

- [internal energy](https://www.gradenine.co.uk/glossary/internal-energy)
- [melting](https://www.gradenine.co.uk/glossary/melting)

## Related

- [Revision notes for AQA GCSE Physics (8463)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe and 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/describe-what-happens-to-the-internal-2bbd2a7e) · Published by Druglandscape Ltd.