1. The problem statement, all variables and given/known data Felder & Rousseau 4.73 (p. 184) A mixture of propane and butane is burned with pure oxygen. The combustion products contain 47.4 mole % H2O. After all of the water is removed from the products, the residual gas contains 69.4 mole% CO2 and the balance is O2. What is the mole percent of propane in the fuel? 2. Relevant equations 1. Let propane = P 2. Choose 100 mol of the reactant fuel as a basis 3. The attempt at a solution Set up 2 balanced equations: 1. C3H8 + 5O2 -> 4H2O + 3CO2 2. C4H8 + 13/2O2 -> 5H2O + 4CO2 I assumed a 100% conversion of the reactant gases. I know O2 is in excess. I drew up a reactant table in terms of mol and set Propane in = P and Butane in= 100-P. I then tried to calculate P by setting the mols of water out divided by the total mols out equal to 0.474.