`C = 12`
`H = 1`
`O = 16`
Let us say we have 100g of reducic acid. Then we have 52.63g of C, 5.3g of H and 42.07g of O in it.
Amount of C moles `= 52.63/12 = 4.39`
Amount of H moles `= 5.3/1 = 5.3`
Amount of O moles `= 42.07/16 = 2.63`
`C:H:O = 4.39:5.3:2.63`
`C:H:O = 4.39/2.63:5.3/2.63:2.63/2.63`
C:H:O = 1.67:2.02:1 = 5:6:3
So the empirical formulae of the acid is `C_5H_6O_3` . There are 5 Carbon atoms is the acid molecule.