# Transition metals can form ions with different oxidation states. Explain why this property makes transition metals and their compounds useful as catalysts, and give one named example of a transition metal or its compound acting as a catalyst in a specific reaction.

> Edexcel A-Level Chemistry (9CH0) — 15.1 Transition metal chemistry · Explain · 5 marks

> Many industrial and biological processes rely on catalysts to increase the rate of reaction. Transition metals are particularly valued for this role due to their variable oxidation states.

## Mark scheme (5 marks)

1. Transition metals have variable oxidation states (can form ions with different charges)
2. This allows the transition metal to accept and then donate electrons to/from reacting particles
3. The catalyst is regenerated / returns to its original oxidation state at the end of the reaction
4. Correct named transition metal or compound acting as a catalyst
5. Correct named reaction or process linked to the named catalyst

## Key terms

- [catalyst](https://www.gradenine.co.uk/glossary/catalyst)
- [transition metal](https://www.gradenine.co.uk/glossary/transition-metal)

## 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)

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Source: [GradeNine](https://www.gradenine.co.uk/q/transition-metals-can-form-ions-with-54dc3e81) · Published by Druglandscape Ltd.