Complete combustion of 2.80 g of a hydrocarbon produced 8.58 g of CO2 and 4.10 g of H2O. What is the empirical formula for the hydrocarbon? empirical formula: CH

Answer 1

To find the empirical formula, we want to find the moles of each element in the compound.

A hydrocarbon is composed on only carbon (C) and hydrogen (H). So we proceed as follows:

moles C: 8.58 g CO2 x 1 mol CO2 / 44 g x 1 mol C / mol CO2 = 0.195 moles C

moles H: 4.10 g H2O x 1 mol H2O / 18 g x 2 mol H / mol H2O = 0.456 moles H

Divide both by 0.195 to try to get whole numbers of moles...

0.195 / 0.195 = 1 mol C

0.456 / 0.195 = 2.34 mo H

Multiply both by 3 to try to get whole numbers of moles...

1 x 3 = 3 mols C

2.34 x 3 = 7 mols H

Empirical formula = C₃H₇