You designed a camping stove that uses liquid propane as fuel and is so efficient that combustion takes place at 120 oC (temperature of the exhaust gas). How much useful heat will this stove produce per 100 g of liquid propane in winter conditions when temperature of the fuel and air are -30 oC? You can assume that air contains pure oxygen and that heat capacities are independent of temperature.
C3H8 (g) + 5O2 --> 3CO2 + 4H2O
Note: Vaporization of propane takes place at -30C.