# A jeweller claims that a sample of metal is pure gold. A technician heats the sample and records the temperature at which it begins to melt and the temperature at which it is completely melted. The technician finds that the sample begins to melt at 1051 °C and is completely melted at 1068 °C. The melting point of pure gold is 1064 °C. Explain what the technician's results tell us about the sample, and describe one further test the technician could carry out to find out more about what the sample contains.

> WJEC A-Level Chemistry (Wales) — 1.3 Chemical bonding · Explain · 5 marks

## Mark scheme (5 marks)

1. The sample is not a pure substance / is a mixture
2. Because it melts over a range of temperatures rather than at a single/sharp melting point
3. A pure substance has a sharp melting point (melts at one specific temperature)
4. Carry out paper chromatography on a dissolved sample (correct method named)
5. This would separate / identify the different substances / components present in the mixture (correct purpose of the further test)

## Key terms

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

## Related

- [Revision notes for WJEC A-Level Chemistry (Wales)](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-jeweller-claims-that-a-sample-0ba9434b) · Published by Druglandscape Ltd.