# Iron reacts with hydrochloric acid according to the balanced equation: Fe + 2HCl → FeCl₂ + H₂. A student adds excess hydrochloric acid to a small amount of iron. Explain what is meant by the term 'limiting reactant' and explain why, in this reaction, the iron acts as the limiting reactant.

> WJEC A-Level Chemistry (Wales) — 3.1 Introduction to organic chemistry · Explain · 5 marks

> Iron reacts with hydrochloric acid according to the balanced equation: Fe + 2HCl → FeCl₂ + H₂. A student adds excess hydrochloric acid to a small amount of iron.

## Mark scheme (5 marks)

1. The limiting reactant is the reactant that is completely used up during the reaction
2. The limiting reactant limits the amount of product(s) formed
3. The hydrochloric acid is added in excess, so there is more HCl than is needed to react with all the iron
4. The iron is completely used up / all the iron reacts
5. Once all the iron has been used up, the reaction stops and no more product can be formed even though HCl remains

## Key terms

- [limiting reactant](https://www.gradenine.co.uk/glossary/limiting-reactant)
- [excess](https://www.gradenine.co.uk/glossary/excess)

## Related

- [Revision notes for WJEC A-Level Chemistry (Wales)](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/iron-reacts-with-hydrochloric-acid-according-2f6a1f46) · Published by Druglandscape Ltd.