# A student has prepared a sample of copper sulfate crystals from a reaction mixture that also contains some unreacted solid copper oxide. Explain how the student could obtain a pure, dry sample of copper sulfate crystals from this mixture.

> Edexcel GCSE Chemistry (1CH0) — 1.2 Methods of separating and purifying substances · Explain · 4 marks

## Mark scheme (4 marks)

1. Filtration is used to remove the insoluble copper oxide from the mixture
2. The filtrate (copper sulfate solution) is collected and heated/evaporated to remove some of the water
3. Leave the concentrated solution to cool, allowing copper sulfate crystals to form by crystallisation
4. Remove the crystals and dry them, for example by patting with filter paper or leaving in a warm oven

## Related

- [Revision notes for Edexcel GCSE Chemistry (1CH0)](https://www.gradenine.co.uk/learn)
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