Use the formula ( Delta H = H_{text{products}} – H_{text{reactants}} )
For reactions at constant pressure, use heat transferred: ( Delta H = q_p )
Use calorimetry data: ( q = mcDelta T )
Convert measured heat to reaction enthalpy by changing the sign if needed
Use standard enthalpies of formation: ( Delta H^circ_{text{rxn}} = sum Delta H^circ_f(text{products}) – sum Delta H^circ_f(text{reactants}) )
Use bond enthalpies: ( Delta H approx sum text{bonds broken} – sum text{bonds formed} )
Use Hess’s law by adding known equations and their enthalpy changes
Check units and express the result in kJ/mol