The Born-Haber cycle for KCl is evaluated with the following data: Δ f H Θ for KCl = − 436.7 kJmol − 1 ; Δ sub H Θ for K = 89.2 kJmol − 1 ; Δ ionization H Θ for K = 419.0 kJ mol − 1 ; Δ electron gain H Θ for Cl ( g ) = − 348.6 kJmol − 1 Δ bond H Θ for Cl 2 = 243.0 kJmol − 1 The magnitude of lattice enthalpy of KCl in kJmol - 1

Step-by-step solution

So, Δ f H Θ = Δ f H Θ KCl = Δ sub  H Θ + Δ 1st ionisation  H Θ K + 1 / 2 Δ bond H Θ Cl 2 ( g ) + Δ electron gain  H Θ + Δ lattice  H Θ - 436 . 7 = 89 . 2 + 419 + 1 2 243 + - 348 . 6 + Δ lattice  H Θ Δ lattice  H Θ = - 717 . 8   kJ   mole - 1 ≈ - 718   kJ   mole - 1