Moles are the bridge
Moles are the bridge

A balanced equation is a counting statement for particles. Its coefficients tell you the ratio in which substances react in moles, so every calculation starts by converting the given information into moles.
Step-by-step lessons on AQA A Level Chemistry Balanced equations and associated calculations. Each one builds up to exam-style questions. Build confidence with atomic structure, bonding and moles calculations early on, since these underpin the more demanding organic mechanisms, equilibrium and practical-analysis topics that dominate Year 2.