Question

Complete combustion of 8.00 g of a hydrocarbon produced 24.5 g of CO2 and 11.7 g of H2O. What is the empirical formula for the hydrocarbon?

Answer 1

C%       = (12/44)* weight of CO2*100/weight of hydrocarbon

            = (12/44)*24.5*100/8

              = 83.5%

H%      = (2/18) * weight of H2O*100/weight of hydrocarbon

       = (2/18)*11.7*100/8

       = 16.25%

     Element           %               A.Wt                   relative number          simple ratio                simplest ratio

      C                   83.5   12 83.5/12 = 6.95                       6.95/6.95 = 1            1*3 = 3

   H 16.25 1    16.25/1    = 16.25                       16.25/6.95 = 2.34     2.34*3 = 7

               Empirical formula = C3H7