# Potassium manganate(VII) has the formula KMnO₄. State the number of atoms of each element present in one formula unit of potassium manganate(VII). Then explain what the term empirical formula means and state whether KMnO₄ is also the empirical formula of potassium manganate(VII), giving a reason for your answer.

> Pearson Edexcel International GCSE Chemistry (4CH1) — 1.5 Chemical formulae, equations and calculations · Explain · 4 marks

## Mark scheme (4 marks)

1. One formula unit of KMnO₄ contains 1 potassium atom, 1 manganese atom and 4 oxygen atoms
2. Empirical formula is the simplest whole number ratio of atoms of each element in a compound
3. KMnO₄ is the empirical formula of potassium manganate(VII)
4. Because the ratio of atoms (1 : 1 : 4) cannot be simplified / divided further to give smaller whole numbers

## Key terms

- [empirical formula](https://www.gradenine.co.uk/glossary/empirical-formula)
- [formula unit](https://www.gradenine.co.uk/glossary/formula-unit)

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Source: [GradeNine](https://www.gradenine.co.uk/q/potassium-manganate-vii-has-the-formula-kmno-94c2f805) · Published by Druglandscape Ltd.