Chemistry - Ionic Equilibrium Question with Solution | TestHub

$\mathrm{C}\mathrm{a}(\mathrm{L}\mathrm{a}\mathrm{C}{)}_2\to \mathrm{C}{\mathrm{a}}^{2+}+2\mathrm{L}\mathrm{a}{\mathrm{C}}^{-}$
Concentration of salt$=\frac{0.6}{2}=0.3$M
Concentration of$\left(\mathrm{L}\mathrm{a}{\mathrm{C}}^{-}\right)$after dissociation$=2\times 0.3\times 0.9=0.54$M
pH after salt hydrolysis may be calculated as,
$\text{pH}\text{=}\frac{\text{1}}{\text{2}}{\text{[(pK}}_{\text{w}}\text{+}{\text{pK}}_{\text{a}}\text{+}{\text{log(LaC}}^{-}\text{)]}$
$14-5.6=\frac{1}{2}[14+\mathrm{p}{\mathrm{K}}_{\mathrm{a}}+\log 0.54]$
$\mathrm{p}{\mathrm{K}}_{\mathrm{a}}=2.8-\log 0.54$