The bond dissociation enthalpies of the H-H bond and the H-Cl bond are 435 kJ mol-1 and 431 kJ mol-1, respectively. The ∆Hºf of HCl (

g. is - 92 kJ mol-1. What is the bond dissociation enthalpy of the Cl-Cl bond?

First, we write the reaction equation for the formation of HCl from hydrogen and chlorine:

H₂ + Cl₂ → 2HCl

Now, we substitute the values of the enthalpies, denoting that of the Cl-Cl bond by x:

435 + x = - 92 + 2 (431)

x = 335

The bond dissociation enthalpy for the Cl-Cl bond is 335 kJ/mol