# A student wants to find out whether a sample of aspirin tablets is pure. She measures the melting point of the aspirin powder and finds that it melts over a range of temperatures rather than at a single sharp temperature. Explain what this result tells the student about the aspirin sample, and describe one further test she could carry out to find out how many substances are present in the sample.

> Eduqas GCSE Chemistry — 1.4 The ever-changing Earth · Explain · 4 marks

## Mark scheme (4 marks)

1. Melting over a range of temperatures shows the aspirin sample is not pure / is a mixture
2. A pure substance melts at a single/sharp specific temperature (so the range confirms impurity)
3. She could carry out paper chromatography on the sample
4. A pure compound produces a single spot on the chromatogram, whereas a mixture produces more than one spot, showing how many substances are present

## Key terms

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

## Related

- [Revision notes for Eduqas GCSE Chemistry](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-wants-to-find-out-61769112) · Published by Druglandscape Ltd.