Values of measured bond energies may vary greatly depending on the molecule studied. Consider the following reactions:
NCl3(g) → NCl2(g) + Cl(g) ΔH = 375 kJ/ mol
ONCl(g) → NO(g) + Cl(g) ΔH = 158 kJ/ mol
Rationalize the difference in the values of ΔH for these reactions, even though each reaction appears to involve the breaking of only one NOCl bond. (Hint: Consider the bond order of the NO bond in ONCl and in NO.)