# Explain what happens to the internal energy and the temperature of a substance as it melts, and explain why the temperature does not change during melting even though energy is being supplied.

> Edexcel GCSE Physics (1PH0) — 14.1 Particle model · Explain · 4 marks

> A student heats a block of ice and notices that, once the ice begins to melt, the temperature of the mixture stays at 0 °C until all the ice has melted, even though the heater is still supplying energy.

## Mark scheme (4 marks)

1. During melting, energy is supplied as latent heat (specific latent heat of fusion) to change the state of the substance.
2. The energy supplied increases the potential energy of the particles (as intermolecular forces are overcome / particles move further apart).
3. The kinetic energy of the particles does not increase during melting.
4. Temperature is a measure of the average kinetic energy of the particles, so because the kinetic energy does not change, the temperature remains constant.

## Key terms

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

## Related

- [Revision notes for Edexcel GCSE Physics (1PH0)](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/explain-what-happens-to-the-internal-ab9581b8) · Published by Druglandscape Ltd.