# Can an empirical formula ever be a molecular formula?

In chemistry, the empirical formula of a chemical compound is the simplest positive integer ratio of atoms present in a compound. A simple example of this concept is that the empirical formula of hydrogen peroxide, or H2O2, would simply be HO. An example of a molucule whose empirical formula is also its molecular formula is methane: $C {H}_{4}$.
These structural formulas all have the same molecular formula ${C}_{3} {H}_{8} O$ ( or ${C}_{3} {H}_{7} O H$), and the same empirical formula, but different structural formulas. The first two are propan-1-ol and propan-2-ol (also called isopropyl alchohol, or rubbing alcohol), The third molecule is another arrangement of ${C}_{3} {H}_{8} O$ called methoxyethane. This third molecule is not even an alcohol like the other two, it is an ether.