# Explain why transition elements are widely used as catalysts in industrial chemical processes.

> Cambridge International IGCSE Chemistry (0620) — 8.4 Transition elements · Explain · 4 marks

> Many important industrial reactions, such as the manufacture of ammonia and the production of sulfuric acid, rely on catalysts made from transition elements.

## Mark scheme (4 marks)

1. Transition elements can have variable oxidation states (variable valency)
2. This allows them to accept and donate electrons during a reaction (or: to form temporary bonds with reactants)
3. The catalyst lowers the activation energy of the reaction
4. The catalyst is not used up / remains chemically unchanged at the end of the reaction

## Key terms

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

## Related

- [Revision notes for Cambridge International IGCSE Chemistry (0620)](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-transition-elements-are-widely-e057099e) · Published by Druglandscape Ltd.