Methane (ch4) at 298 k, 1 atm enters a furnace operating at steady state and burns completely with 140% of theoretical air entering at 400 k, 1 atm. the products of combustion exit at 500 k, 1 atm. the flow rate of the methane is 1.4 kg/min. kinetic and potential energy effects are negligible and air can be modeled as 21% o2 and 79% n2 on a molar basis.