Question

A .438 g of sample of a compound containing only C and H is combusted in oxygen producing 1.481 g of CO2 and .303 g of H2O. What is the empirical formula of the compound?

Answer 1

Answer -

We have work backward. You know the formula for combustion.

combustion of the hydrocarbon.

Compound + O2 = CO2 + H2O

mols of H2O = 0.303 / (1*2+16) = 0.01683 mols

mols of CO2 = 1.481 / (12+16*2) = 0.03366 mols

Divided by smaller number of moles to got a whole number.

0.03366 / 0.01683 = 2

ratio of H2O : CO2 is 1 : 2

ratio of H2O : H is 1 : 2

therefore, ratio of C : H is 1 : 1

Empirical formula: CH

Hence, the empirical formula of the compund is CH.