Emperical formula?

Question

a 27.0 g sample of an unknown hydrocarbon CxHy is burned in excess oxygen to form 88.0 g of C02 and 27.0 g of H20. What is the empirical formula?

Answer 1

CO2 has a mole wt of 44, so we have formed 2 moles of CO2, and have 2 g-atoms of C available from our sample. H2O has a mole wt of 18, so we have 3 g-atoms of H available from our sample. That accounts for 27 grams. So the empirical formula would be C2H3.