# Explain why magnesium is a more effective reducing agent than iron, using standard electrode potentials to support your answer.

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

> Standard electrode potentials (E°) at 298 K: Mg²⁺(aq) + 2e⁻ ⇌ Mg(s), E° = −2.37 V; Fe²⁺(aq) + 2e⁻ ⇌ Fe(s), E° = −0.44 V.

## Mark scheme (4 marks)

1. A reducing agent is a species that donates electrons (is oxidised) in a redox reaction.
2. A more negative standard electrode potential indicates a greater tendency to be oxidised (lose electrons).
3. Magnesium has a more negative E° (−2.37 V) than iron (−0.44 V), so magnesium has a greater tendency to be oxidised.
4. Therefore magnesium donates electrons more readily than iron and is a stronger reducing agent.

## Key terms

- [reducing agent](https://www.gradenine.co.uk/glossary/reducing-agent)
- [standard electrode potential](https://www.gradenine.co.uk/glossary/standard-electrode-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)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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