અથવા \(\begin{gathered} {{\text{I}}_{{\text{(g)}}}} + C{l_{(g)}} \to IC{l_{(g)}} \hfill \\ \therefore \,\,\Delta H = \frac{1}{2}{(B.E.)_{{I_2}}} + \frac{1}{2}{(B.E.)_{C{l_2}}} - {(B.E.)_{I - Cl}} \hfill \\17.57 = 106.96 + 121.34 - {(B.E.)_{I - Cl}} \hfill \\ {(B.E.)_{I - Cl}} = 210.73\,\,J\,\,mol{e^{ - 1}} \hfill \\ \end{gathered} \)