# A student prepares a solution of copper sulfate (CuSO₄) by dissolving 0.20 mol of copper sulfate in water to make 250 cm³ of solution. Explain how the concentration of this solution would change if the student had instead dissolved the same 0.20 mol of copper sulfate in water to make 500 cm³ of solution.

> AQA GCSE Chemistry (8462) — 4.3.4 Using concentrations of solutions in mol/dm³ (Chem only) · Explain · 4 marks

## Mark scheme (4 marks)

1. The concentration would decrease / be lower / be smaller
2. Because the volume of solution has increased (doubled) / the same number of moles is dissolved in a larger volume
3. Concentration = moles ÷ volume (in dm³), so the original concentration is 0.80 mol/dm³
4. The new concentration is 0.40 mol/dm³ (0.20 mol ÷ 0.500 dm³)

## Key terms

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

## Related

- [Revision notes for AQA GCSE Chemistry (8462)](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-prepares-a-solution-of-cc99cb23) · Published by Druglandscape Ltd.