C5H4
Calculate how many moles of hydrogen and carbon you have in the products. Do this by lookup up the atomic weights of each element in the products
Carbon = 12.0107
Hydrogen = 1.00794
Oxygen = 15.999
Using those atomic weights, calculate the molar mass of each product
CO2 = 12.0107 + 2 * 15.999 = 44.0087
H2O = 2 * 1.00794 + 15.999 = 18.01488
Now figure out how many moles of each product was produced.
CO2: 8.80 g / 44.0087 g/mol = 0.19996 mol
H2O: 1.44 g / 18.01488 g/mol = 0.079934 mol
Moles of carbon = 0.19996, moles of hydrogen = 2 * 0.079934 = 0.159868
Now we need to find a ratio of small integers that closely approximates 0.19996 / 0.159868 = 1.250782
The closest ratio is 5/4 which indicates that for every 5 carbon atoms, there are 4 hydrogen atoms, so the empirical formula is C5H4.
