moles CO2 = 0.2998 g CO2 x 1 mole/44 g = 0.006814 moles CO2
mole C = 0.006814 moles CO2 x 1 mole C/mole CO2 = 0.006814 moles C
moles H2O = 0.0819 g H2O x 1 mole/18 g = 0.00455 moles H2O
moles H = 0.00455 moles H2O x 2 moles H/mole H2O = 0.0091 moles H
In order to find mass of oxygen (O) in the compound, we need to first convert the moles of C and mole of H to grams.
0.006814 moles C x 12 g/1 mole = 0.08177 g Carbon
0.0091 moles H x 1 g/1 mole = 0.0091 g Hydrogen
Total mass of C and H = 0.08177 g + 0.0091 g = 0.09087 g
Grams of O = 0.2000 g - 0.09087 g = 0.1091 g
moles O = 0.1091 g O x 1 mole/16 g = 0.006818 moles O
Now, to get the empirical formula, use moles C, moles H and moles O
C = 0.00681
H = 0.0091
O = 0.00681
Divide all by the smallest, i.e. 0.00681 to get ...
C = 1.00
H = 1.33
O = 1.00
Now, multiply all by 3 to get whole numbers, and the answer is...
C3H4O3 = empirical formula for ascorbic acid