# A student is investigating the specific latent heat of fusion of ice. They place crushed ice into an insulated container and record the temperature every 30 seconds as the ice melts. They notice that the temperature stays at 0 °C for several minutes before it begins to rise. Explain what the student should do to make their results more reliable, and explain why the temperature remains constant at 0 °C even though heat energy is continuously being supplied to the ice.

> OCR A-Level Physics A (H556) — 1.1 Practical skills assessed · Explain · 5 marks

> A student is investigating the specific latent heat of fusion of ice. They place crushed ice into an insulated container and record the temperature every 30 seconds as the ice melts.

## Mark scheme (5 marks)

1. The student should repeat the experiment (at least twice/multiple times) and calculate a mean/average temperature reading (or mean time at 0 °C)
2. The student should use a thermometer with a suitable resolution / small scale divisions (e.g. 0.1 °C) to detect small temperature changes accurately
3. The student should stir the contents of the container regularly / continuously to ensure the temperature reading is representative of the whole mixture
4. The energy supplied is being used to break the intermolecular forces / bonds between particles (to change state) rather than to increase the kinetic energy of the particles
5. Because temperature is a measure of the average kinetic energy of the particles, and the kinetic energy of the particles does not increase during the change of state, the temperature does not rise

## Key terms

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

## Related

- [Revision notes for OCR A-Level Physics A (H556)](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-investigating-the-specific-809c808e) · Published by Druglandscape Ltd.