GCSE Chemistry revision

Using moles to balance equations

Use of amount of substance in relation to masses of pure substances

AQA 4.3.2.3 Higher Tier only

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The numbers (coefficients) in a balanced chemical equation represent the ratio of moles of each substance reacting or being produced.
For example, in Mg + 2HCl → MgCl₂ + H₂, 1 mole of Mg reacts with 2 moles of HCl to produce 1 mole of MgCl₂ and 1 mole of H₂.
These mole ratios can be scaled up or down; for instance, 2 moles of Mg would require 4 moles of HCl and produce 2 moles of MgCl₂ and 2 moles of H₂.

1. Moles in Chemical Equations AQA

The numbers (coefficients) in a balanced chemical equation represent the ratio of moles of each substance reacting or being produced.
For example, in Mg + 2HCl → MgCl₂ + H₂, 1 mole of Mg reacts with 2 moles of HCl to produce 1 mole of MgCl₂ and 1 mole of H₂.
These mole ratios can be scaled up or down; for instance, 2 moles of Mg would require 4 moles of HCl and produce 2 moles of MgCl₂ and 2 moles of H₂.