# Explain why a galvanic cell constructed from a zinc half-cell connected to a copper half-cell produces a positive cell potential, and identify which electrode acts as the anode, giving a reason based on standard electrode potential values.

> IB DP Chemistry Higher Level (2023 syllabus) — R3.2 Electron transfer reactions · Explain · 4 marks

> Standard electrode potentials (E°) at 298 K: Zn²⁺(aq)/Zn(s): −0.76 V; Cu²⁺(aq)/Cu(s): +0.34 V.

## Mark scheme (4 marks)

1. The cell potential is positive because it is calculated as E°(cathode) − E°(anode), i.e. +0.34 − (−0.76) = +1.10 V, giving a positive value.
2. Zinc is the anode (site of oxidation) because it has the more negative / less positive standard electrode potential (−0.76 V).
3. At the anode, zinc is oxidised: Zn(s) → Zn²⁺(aq) + 2e⁻, releasing electrons into the external circuit.
4. The positive cell potential indicates a spontaneous reaction / a negative Gibbs energy change (ΔG° < 0), because ΔG° = −nFE°cell.

## Key terms

- [standard electrode potential](https://www.gradenine.co.uk/glossary/standard-electrode-potential)
- [galvanic cell](https://www.gradenine.co.uk/glossary/galvanic-cell)
- [anode](https://www.gradenine.co.uk/glossary/anode)
- [cell potential](https://www.gradenine.co.uk/glossary/cell-potential)

## Related

- [Revision notes for IB DP Chemistry Higher Level (2023 syllabus)](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/explain-why-a-galvanic-cell-constructed-b81ff1d2) · Published by Druglandscape Ltd.