# Magnesium nitrate has the formula Mg(NO₃)₂. State what is meant by the term relative formula mass and describe how the relative formula mass of magnesium nitrate is determined from its formula.

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

> Magnesium nitrate, Mg(NO₃)₂, is used as a fertiliser. The relative atomic masses are: Mg = 24, N = 14, O = 16.

## Mark scheme (4 marks)

1. Relative formula mass is the sum of the relative atomic masses of all the atoms in the formula
2. Correctly identifies the number of each type of atom: 1 Mg, 2 N, 6 O
3. Correctly multiplies each relative atomic mass by the number of those atoms: 24 + (2 × 14) + (6 × 16)
4. Arrives at the correct relative formula mass of 148

## Key terms

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

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Source: [GradeNine](https://www.gradenine.co.uk/q/magnesium-nitrate-has-the-formula-mg-no-7da06d61) · Published by Druglandscape Ltd.