Mass of hydrocarbon = 7.60 g
All the C gets converted to 23.4 g of CO2
All the H gets converted to 10.8 g of H2O
Now:
Molecular mass of CO2 = 48 g/mol
Molecular mass of H2O = 18 g/mol
# moles of CO2 = 23.4 g/48 gmol-1 = 0.4875 = moles of C
# moles of H2O = 10.8/18 = 0.6 moles = moles of H
Now:
Mass of C = 0.4875 moles * 12 g/mole = 5.85 g
Mass of H = 0.6 moles * 1 g/mole = 0.6 g
Total mass = C + H = 5.85 + 0.6 = 6.45 g. Ideally, this must be equal to the given mass of the hydrocarbon, 7.60 g.
Nevertheless, in order to find the empirical formula, divide the # moles of C and H by the smallest value:
C = 0.4875/0.4875 = 1
H = 0.6/0.4875 = 1.23 (approximately = 1)
Empirical formula = CH
