# Explain why the temperature of a substance does not change whilst it is boiling, even though it is continuously being heated.

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

> A student heats a beaker of water until it reaches its boiling point. She notices that the thermometer reading stays constant throughout the boiling process, even though the Bunsen burner remains lit.

## Mark scheme (4 marks)

1. During boiling, the energy supplied goes into changing state (breaking intermolecular forces / overcoming forces between particles) rather than increasing the kinetic energy of the particles.
2. This energy is the latent heat (specific latent heat of vaporisation) of the substance.
3. Because the kinetic energy of the particles does not increase, the temperature does not rise.
4. The energy instead increases the potential energy of the particles, allowing them to separate and become a gas.

## Key terms

- [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-why-the-temperature-of-a-60ca6a0e) · Published by Druglandscape Ltd.