Using data from the following reactions and applying Hess's law, calculate the heat change for the slow reaction of zinc with water:
Zn (s) + 2H2O (l) → Zn2+ (aq) + 2OH- (aq) + H2 (g) ΔH°rxn = ?
H+ (aq) + OH- (aq) → H2O (l) ΔH°rxn, 1 = -56 kJ/mol H2O
Zn (s) → Zn2+ (aq) ΔH°rxn, 2 = -153.9 kJ
1/2 H2 (g) → H+ (aq) ΔH°rxn, 3 = 0.0 kJ