The chemical equation for the complete combustion of propane C3H8 is:C3H8 + 5O2 3CO2 + 4H2OIn this reaction, one molecule of propane reacts with five molecules of oxygen O2 to produce three molecules of carbon dioxide CO2 and four molecules of water H2O . Therefore, for the complete combustion of propane, five molecules of oxygen are required for each molecule of propane.