# A student is heating a block of ice. At first, the temperature of the ice rises. Then, for a period of time, the temperature stops rising even though the student continues to supply heat energy. Explain why the temperature stops rising during this period, using the idea of latent heat.

> OCR GCSE Physics A: Gateway Science (J249) — P1.2 Changes of state · Explain · 4 marks

> A student places a block of ice in a beaker and heats it steadily using a Bunsen burner. The student notices that the temperature of the contents remains constant for several minutes before it begins to rise again.

## Mark scheme (4 marks)

1. The ice is changing state (melting) from solid to liquid during this period.
2. The energy supplied is used to overcome the intermolecular forces between particles / break bonds between particles, rather than increasing their kinetic energy.
3. Because temperature is a measure of the average kinetic energy of the particles, and kinetic energy is not increasing, the temperature does not rise.
4. The energy required to change state at constant temperature is called latent heat (specific latent heat of fusion for melting).

## Key terms

- [latent heat](https://www.gradenine.co.uk/glossary/latent-heat)
- [temperature](https://www.gradenine.co.uk/glossary/temperature)

## Related

- [Revision notes for OCR GCSE Physics A: Gateway Science (J249)](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-is-heating-a-block-cbff9871) · Published by Druglandscape Ltd.