Empirical and molecular formulae: Percentage composition by mass, water of crystallisation and formula determination

What this note covers

1. Three kinds of formula, and which one a question wants
2. Percentage composition by mass
3. Empirical formula from percentage composition
4. From empirical formula to molecular formula
5. Water of crystallisation
6. Empirical formula from combustion data
7. Presenting the calculation so it earns full marks
8. How this topic is examined in Section E

8 sections · 12 key terms & formulas · 6 common mistakes