If the solubility of $\mathrm{Pb}_{3}\left(\mathrm{PO}_{4}\right)_{2}$ is S moles per litre, Ksp of

Question

If the solubility of $\mathrm{Pb}_{3}\left(\mathrm{PO}_{4}ight)_{2}$ is S moles per litre, Ksp of this salt will be\

Professor PC Thomas Classes · Answer

$\mathrm{Pb}_{3} \underset{\mathrm{~S}}{\left(\mathrm{PO}_{4}ight)_{2}} \underset{3 \mathrm{~S}}{ightleftarrows 3 \mathrm{~Pb}^{2+}}+\underset{2 \mathrm{~S}}{2 \mathrm{PO}_{4}^{3-}}$ $$ \begin{aligned} & \mathrm{k}_{\mathrm{sp}}=\left[\mathrm{Pb}^{2+}ight]^{3} 	imes\left[\mathrm{PO}_{4}^{3-}ight]^{2}=(3 \mathrm{~s})^{3} 	imes(2 \mathrm{~s})^{2} \ & =27 \mathrm{~s}^{3} 	imes 4 \mathrm{~s}^{2}=108 \mathrm{~s}^{5} \end{aligned} $$