Reaction Enthalpy (Hess's Law)

ΔH°rxn = Σ n·ΔH°f(products) − Σ n·ΔH°f(reactants). List each species as coefficient × ΔHf in kJ/mol, for example "1*-393.5, 2*-285.8". Elements in their standard state have ΔHf = 0. A negative result means the reaction is exothermic.