propane in a furnace that uses 20% excess? caluclate the quantity of air needed for the combustion of 220 gm of propane in a furnace that uses 20% excess air.calculate the volume of air at pressure of 750 mmHg and a temperature of 32 c. if the combustion products were cooled to 120 c and a pressure of 730 mmHg,Calculate the volume and the density of the combustion products and the partial pressure of CO2