The standard heat of combustion of butane gas, C4H10, at 25 ° C is - 2.880 x 103 kJ mol-1 when the products are CO2 (g) and H2O (l). Calculate the value of ΔH ° if the combustion products are CO2 (g) and H2O (g). given: CO2 (g) = ΔHf ° - 393.5 kJmol-1; H2O (l) = ΔHf ° -285.8 kJmol-1; H2O (g) = ΔHf ° -241.8 kJmol -1.