Compute the heats of combustion for the following reactions from the standard enthalpies of formation listed in Appendix 3.(→?H°f (HgO(s)) = -90.7 kJ/mol and ?H°f (FeO(s)) = -272 kJ/mol.)
(a) 2 H2(g) +O2(g) → 2H2O(l)
(b) 2 CH3OH(l) + 3 O2(g)→ 2CO2(g) + 4 H2O(l)