# Sodium chloride solution is electrolysed using inert electrodes. Explain why chlorine gas is produced at the anode rather than oxygen, and identify the product formed at the cathode, explaining why that product forms instead of sodium metal.

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

## Mark scheme (4 marks)

1. Chlorine is produced at the anode because the solution contains chloride (halide) ions
2. The anode is the positive electrode where negatively charged chloride ions lose electrons (oxidation)
3. Hydrogen gas is produced at the cathode
4. Hydrogen is produced instead of sodium because sodium is more reactive than hydrogen, so hydrogen ions are preferentially discharged at the cathode

## Key terms

- [anode](https://www.gradenine.co.uk/glossary/anode)
- [cathode](https://www.gradenine.co.uk/glossary/cathode)
- [inert electrode](https://www.gradenine.co.uk/glossary/inert-electrode)

## 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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