The enthalpies of formation of the compounds in the combustion of methane,

Upper C upper H subscript 4 (g) plus 2 upper O subscript 2 (g) right arrow upper C upper o subscript 2 (g) plus 2 upper H subscript 2 upper O (g).,

are CH4 (g): Delta.Hf = –74.6 kJ/mol; CO2 (g): Delta.Hf = –393.5 kJ/mol; and H2 O(g): Delta.Hf = –241.82 kJ/mol.

How much heat is released by the combustion of 2 mol of methane?
Use Delta H r x n equals the sum of delta H f of all the products minus the sum of delta H f of all the reactants..