# A student is heating a block of ice. The student notices that, whilst the ice is melting, the temperature of the substance does not rise even though heat energy is continuously being supplied. Explain why the temperature does not rise during melting, and describe what happens to the mass of the substance during this change of state.

> OCR GCSE Physics A: Gateway Science (J249) — P1.1 The particle model · Explain · 4 marks

> A block of ice is placed in a beaker and heated steadily on a hotplate. A thermometer placed in the beaker shows that the temperature stays constant whilst ice and liquid water are both present, even though heating continues.

## Mark scheme (4 marks)

1. During melting, the energy supplied is used to break the intermolecular forces / bonds between particles (rather than raise temperature).
2. The energy supplied during melting is called latent heat (specific latent heat of fusion).
3. Because the energy goes into changing state rather than increasing the average kinetic energy of the particles, the temperature remains constant.
4. Mass is conserved during the change of state, so the mass of the liquid water produced equals the mass of the ice that melted.

## Key terms

- [melting](https://www.gradenine.co.uk/glossary/melting)
- [temperature](https://www.gradenine.co.uk/glossary/temperature)
- [mass](https://www.gradenine.co.uk/glossary/mass)

## 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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-is-heating-a-block-19e69295) · Published by Druglandscape Ltd.