Question

Can the molecular formula of a compound ever be the same as the empirical formula?

Answer 1

Certainly. Remember that the empirical formula is the simplest ratio of atoms in a molecule. In some cases, the molecular formula cannot be simplified further.

A good example of this is ethanol, `C_2H_6O` (`CH_3CH_2OH`). As there is only one oxygen atom in the molecule, this molecular formula cannot be simplified, so this is also its empirical formula.

It is also worth remembering why we learn about empirical formulae. Percentage composition information will lead to an empirical formula, not necessarily the molecular formula. We use the molar mass to determine the molecular formula from the empirical formula.