# Aluminium chloride has the formula AlCl₃. State what is meant by the term relative formula mass and describe the steps you would follow to find the relative formula mass of aluminium chloride. Use the relative atomic masses: Al = 27, Cl = 35.5.

> Pearson Edexcel International GCSE Chemistry (4CH1) — 1.4 Relative formula mass · State and Describe · 4 marks

## Mark scheme (4 marks)

1. Relative formula mass is the sum of the relative atomic masses of all the atoms in a formula
2. Identify the number of atoms of each element: one Al atom and three Cl atoms
3. Multiply the relative atomic mass of each element by the number of its atoms: 1 × 27 = 27 and 3 × 35.5 = 106.5
4. Add the results to obtain the relative formula mass: 27 + 106.5 = 133.5

## Key terms

- [relative formula mass](https://www.gradenine.co.uk/glossary/relative-formula-mass)
- [relative atomic mass](https://www.gradenine.co.uk/glossary/relative-atomic-mass)
- [formula](https://www.gradenine.co.uk/glossary/formula)

## Related

- [Revision notes for Pearson Edexcel International GCSE Chemistry (4CH1)](https://www.gradenine.co.uk/learn)
- [How to answer "State and Describe" 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/aluminium-chloride-has-the-formula-alcl-00a5a857) · Published by Druglandscape Ltd.