The empirical formula is the simplest possible formula for a compound.
The molecular formula of CH 3 COOH can be written as C2H4O2 . The ratios of C: H:O are 2:4:2.
The highest common factor of 2 and 4 is 2.
Then divide each of these numbers by 2 to get the ratio C:H:O=1:2:1
The empirical formula of acetic acid is then CH2O .