# A student electrolyses copper(II) sulfate solution using copper electrodes instead of inert electrodes. Explain what happens at each electrode during this electrolysis, and explain why the concentration of copper(II) sulfate solution remains constant throughout the process.

> Pearson Edexcel International GCSE Chemistry (4CH1) — 1.9 Electrolysis · Explain · 4 marks

## Mark scheme (4 marks)

1. At the cathode, copper(II) ions gain electrons / are reduced to form copper metal deposited on the electrode
2. At the anode, copper atoms from the copper electrode lose electrons / are oxidised to form copper(II) ions which pass into solution
3. The rate at which copper ions are removed at the cathode equals the rate at which copper ions are released at the anode
4. Therefore the overall concentration of copper(II) sulfate solution does not change / stays constant

## Key terms

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

## Related

- [Revision notes for Pearson Edexcel International GCSE Chemistry (4CH1)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-electrolyses-copper-ii-sulfate-solution-bcc40a47) · Published by Druglandscape Ltd.