# A student is given two white powder samples. One is pure aspirin and the other is an aspirin tablet that has been crushed. Explain how the student could use melting point data to determine which sample is the pure substance, and what results they would expect for each sample.

> WJEC GCSE Chemistry (Wales) — 1.1 The nature of substances and chemical reactions · Explain · 4 marks

## Mark scheme (4 marks)

1. Heat both samples and record the temperature(s) at which each melts
2. The pure substance melts at a single/sharp temperature
3. The impure sample (crushed tablet) melts over a range of temperatures
4. The pure substance can be identified because a pure substance contains only one element or compound, whereas the tablet is a mixture and mixtures melt over a range of temperatures

## Key terms

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

## Related

- [Revision notes for WJEC GCSE 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-student-is-given-two-white-9bff5875) · Published by Druglandscape Ltd.