Understanding Chemical Formulae
The key difference between empirical and molecular formulae is simpler than it looks. Think of empirical formulae as the "simplified version" - it shows the smallest whole number ratio of atoms in a compound.
Molecular formulae tell you the actual number of each type of atom present. For example, ethane has the molecular formula C₂H₆, but its empirical formula is just CH₃. You can see that C₂H₆ is simply CH₃ × 2.
The essential formula you'll need is n = m/M, where n is moles, m is mass, and M is molar mass. This relationship is your best friend for all molecular formula calculations.
Quick Tip: Empirical formulae are mainly used for giant structures like metals and ionic compounds, whilst molecular formulae apply specifically to molecules.
