Final answer:
To find the empirical formula of a hydrocarbon, calculate the moles of carbon and hydrogen from the masses of CO2 and H2O produced in combustion. Then find the smallest whole-number molar ratio to determine the empirical formula.
Step-by-step explanation:
To determine the empirical formula of a hydrocarbon that produces 22 g of CO2 and 27.0 g of H2O upon complete combustion, start by calculating the molar amounts of carbon and hydrogen in the sample:
- Each mole of CO2 contains 1 mole of carbon, so from 22 g of CO2, we calculate the moles of carbon using the molar mass of CO2 (44.01 g/mol).
- Each mole of H2O contains 2 moles of hydrogen, so from 27.0 g of H2O, we calculate the moles of hydrogen using the molar mass of H2O (18.02 g/mol).
Divide the calculated moles by the smallest number of moles to get the ratio. The smallest whole-number ratio gives the empirical formula.
For example, from the CO2, we get (22 g CO2) / (44.01 g/mol) = 0.5 mol C. From the H2O, we get (27.0 g H2O) / (18.02 g/mol) = 1.5 mol H. The ratio of hydrogen to carbon is 3:1, giving a provisional empirical formula of CH3. However, actual computation should be done to confirm the formula.