# A student compares two acids: hydrochloric acid and methanoic acid, both at a concentration of 0.01 mol/dm³. Explain why the electrical conductivity of the hydrochloric acid solution is greater than that of the methanoic acid solution at the same concentration.

> AQA A-Level Chemistry (7405) — 3.1.12 Acids and bases (A-Level only) · Explain · 5 marks

> Hydrochloric acid is a strong acid. Methanoic acid is a weak acid.

## Mark scheme (5 marks)

1. Strong acids fully/completely dissociate (in water)
2. Weak acids only partially dissociate (in water), establishing an equilibrium
3. Hydrochloric acid produces a greater concentration of ions / more ions in solution than methanoic acid at the same concentration
4. Electrical conductivity depends on the concentration / number of ions (that can carry charge / current)
5. Therefore hydrochloric acid has higher conductivity because it has a greater concentration of ions than methanoic acid at the same concentration

## Key terms

- [electrical conductivity](https://www.gradenine.co.uk/glossary/electrical-conductivity)
- [concentration](https://www.gradenine.co.uk/glossary/concentration)

## Related

- [Revision notes for AQA A-Level Chemistry (7405)](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/a-student-compares-two-acids-hydrochloric-dab8bf4a) · Published by Druglandscape Ltd.