QJEEM21Ch8585: JEE Main 2021 Chemistry - Class 11 JEEM21Ch8585 Solution: The Born-Haber cycle for KCl is evaluated with the following…

Question

Verified Solution • 2025–26 Session moderate

The Born-Haber cycle for KCl is evaluated with the following data :

{\Delta _f}{H^\Theta }

for KCl =

-

436.7 kJ mol^{$-$ 1} ;

{\Delta _{sub}}{H^\Theta }

for K = 89.2 kJ mol^{$-$ 1} ;

{\Delta _{ionization}}{H^\Theta }

for K = 419.0 kJ mol^{$-$ 1} ;

{\Delta _{electron\,gain}}{H^\Theta }

for Cl_(g) =

-

348.6 kJ mol^{$-$ 1} ;

{\Delta _{bond}}{H^\Theta }

for Cl₂ = 243.0 kJ mol^{$-$ 1}

The magnitude of lattice enthalpy of KCl in kJ mol^{$-$ 1} is _____________ (Nearest integer)

Accepted Answer

{\Delta _f}H_{KCl}^\Theta = {\Delta _{sub}}H_{(K)}^\Theta + {\Delta _{ioniztion}}H_{(K)}^\Theta + {1 \over 2}{\Delta _{bond}}H_{(C{l_2})}^\Theta + {\Delta _{electron\,gain}}H_{(Cl)}^\Theta + {\Delta _{lattice}}H_{(KCl)}^\Theta

\Rightarrow - 436.7 = 89.2 + 419.0 + {1 \over 2}(243.0) + \{ - 348.6\} + {\Delta _{lattice}}H_{(KCl)}^\Theta

\Rightarrow {\Delta _{lattice}}H_{(KCl)}^\Theta = - 717.8

kJ mol^{$-$ 1}

The magnitude of lattice enthalpy of KCl in kJ mol^{$-$ 1} is 718 (Nearest integer).

Step-by-Step Verified Solution