# A student sets up an electrochemical cell using a zinc half-cell and a copper half-cell connected by a salt bridge. The standard electrode potentials are: Zn²⁺/Zn = −0.76 V and Cu²⁺/Cu = +0.34 V. Explain how the electrochemical cell produces a voltage, including the role of the salt bridge.

> Edexcel A-Level Chemistry (9CH0) — 14.1 Electrode potentials and electrochemical cells · Explain · 5 marks

> An electrochemical cell consists of two half-cells: a zinc electrode in zinc sulfate solution and a copper electrode in copper sulfate solution. The two solutions are connected by a salt bridge soaked in potassium nitrate solution.

## Mark scheme (5 marks)

1. Oxidation occurs at the zinc electrode / zinc loses electrons
2. Reduction occurs at the copper electrode / copper ions gain electrons
3. Electrons flow through the external circuit from zinc to copper
4. The difference in electrode potentials between the two half-cells causes / drives the voltage (e.m.f.)
5. The salt bridge completes the circuit by allowing ions to move between the two half-cell solutions, maintaining electrical neutrality

## Key terms

- [electrode potential](https://www.gradenine.co.uk/glossary/electrode-potential)
- [salt bridge](https://www.gradenine.co.uk/glossary/salt-bridge)
- [electrochemical cell](https://www.gradenine.co.uk/glossary/electrochemical-cell)

## Related

- [Revision notes for Edexcel A-Level Chemistry (9CH0)](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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-sets-up-an-electrochemical-bf39e13e) · Published by Druglandscape Ltd.