The enthalpies of formation of the compounds in the combustion of methane, ,are CH4 (g): Hf = –74.6 kJ/mol; CO2 (g): Hf = –393.5 kJ/mol; and H2 O(g): Hf = –241.82 kJ/mol.How much heat is released by the combustion of 2 mol of methane? Use .