# A student carries out tests on a sample of tap water to find out whether it is pure water. Describe the tests the student could carry out and explain how the results would show whether the water is pure.

> Eduqas GCSE Chemistry — C8 Chemical analysis · Describe · 4 marks

## Mark scheme (4 marks)

1. The student could measure the boiling point of the sample
2. Pure water boils at exactly 100 °C; a boiling point above 100 °C indicates impurities are present
3. The student could measure the melting point (freezing point) of the sample
4. Pure water melts/freezes at exactly 0 °C; a melting point below 0 °C indicates impurities are present

## Key terms

- [pure water](https://www.gradenine.co.uk/glossary/pure-water)

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- [Revision notes for Eduqas GCSE Chemistry](https://www.gradenine.co.uk/learn)
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Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-carries-out-tests-on-8b3168af) · Published by Druglandscape Ltd.