The empirical formula of a compound is the simplest, whole number ratio of atoms of each element in a compound.
The molecular formula shows the actual number of atoms of each element present in a compound.
|Molecular formula||Empirical formula|
You can work out the molecular formula from the empirical formula, if you know the relative mass formula (Mr) of the compound.
Add up the atomic masses of the atoms in the empirical formula.
The empirical formula of a hydrocarbon is CH2 and its Mr is 42.
The molecular formula of the hydrocarbon is C3H6.