To balance the chemical equation for the combustion of propane, we need to make sure that the number of atoms of each element on the reactant side is equal to the number of atoms of each element on the product side.Unbalanced equation: C3H8 + O2 CO2 + H2O1. Balance the carbon atoms:C3H8 + O2 3CO2 + H2O2. Balance the hydrogen atoms:C3H8 + O2 3CO2 + 4H2O3. Balance the oxygen atoms:C3H8 + 5O2 3CO2 + 4H2OThe balanced chemical equation for the combustion reaction of propane with oxygen gas to produce carbon dioxide gas and water vapor is:C3H8 + 5O2 3CO2 + 4H2O