Which statement best describes how bond energies relate to the enthalpy change, ΔH, of a chemical reaction?
a) ΔH is calculated by subtracting the total energy released when new bonds form from the total energy required to break bonds in the reactants.
b) ΔH is calculated by subtracting the total energy required to break bonds from the total energy released when new bonds form.
c) ΔH equals the sum of the energies for all bonds broken and formed, because both processes add to the enthalpy change.
d) ΔH equals the difference between the total bond energies of the products and those of the reactants, without distinguishing bond breaking from bond forming.