# A student has two white powder samples. One sample is a pure substance and the other is a mixture. Describe how the student could use melting point data to determine which sample is the pure substance, and explain what results would be expected for each sample.

> Eduqas A-Level Chemistry — 1.4 States of matter · Describe · 5 marks

## Mark scheme (5 marks)

1. Heat both samples and record the temperature(s) at which each sample melts
2. The pure substance will have a sharp (single, specific) melting point
3. The mixture will melt over a range of temperatures
4. The sample that shows a sharp melting point is identified as the pure substance
5. The recorded melting point can be compared to a known/data book value to confirm the identity of the pure substance

## Key terms

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

## Related

- [Revision notes for Eduqas A-Level Chemistry](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-has-two-white-powder-f2f6c8a4) · Published by Druglandscape Ltd.