Question

The hydration energies of \(K^+\) and \(Cl^-\) are -x and -y kJ/mol respectively. If lattice energy of KCl is -z kJ/mol, then the heat of solution of KCl is :

(1) + x - y - z

(2) x + y + z

(3) z - ( x + y)

(4) - z - ( x + y)

Answer 1

Correct option is: (3) z - ( x + y )

\(\Delta H_{\text{solution}} = (- \Delta H _{L.E.}) + \Delta_{\text{hydration}}\)

\(= - (-z) + (-x - y)\)

\(= z - (x+y)\)