Calculate the approximate enthalpy change, δhrxn, for the combustion of methane:
ch4+2o2→2h2o+co2

δhrxn from a given table:
ch4 = 1656 kj/mol
o2 = 498 kj/mol
h2o = 928 kj/mol
co2 = 1598 kj/mol
δhrxn = [(1656) + (2*498)] - [(2*928) + (1598)] = -802 kj/mol ?