IN THE SOLUTION , WHY IS THE UNDERLINED STEP USED ?
H reactants- H products is for BOND ENTHALPIES RIGHT ?
The heat of combustion of C2H6 is -368.4 kcal. Calculate heat of combustion of C2H4, heat of combustion of H2 is kcal/mol . Delta H for the following reaction is -37.1 kcal.
C2H4(g) + H20(g) --> C2H6(g)

IN THE SOLUTION , WHY IS THE UNDERLINED STEP USED ? H reactants- H products is for BOND ENTHALPIES RIGHT ? The heat of combustion of C2H6 is -368.4 kcal. Calculate heat of combustion of C2H4, heat of combustion of H2 is kcal/mol . Delta H for the following reaction is -37.1 kcal. C2H4(g) + H20(g) --> C2H6(g) Calonnc value rn = 52 x 30 = 1560 kJ/m01 28. + C2H6(g) AH = - 37.1 - 368.4 kcal, c:H4 = ? = -68.32 kcal SAH (products) AcHC2H4 + AcHH2(g) -37.1 kcal = 68.32 368.4) C2H4= -337.18 kcal