Question

Calculate pH of saturated solution of $Mg(OH{)}_2,K_{sp}$ for $Mg(OH{)}_2$ is $32.0\times {10}^{-12}$.
$\text{Given :}\log 2=0.3010$

• A. $9.4$
• B. $11.2$
• C. $10.4$
• D. $9.8$

Answer 1

The correct option is C $10.4$

$Mg(OH{)}_2\rightleftharpoons \underset{s}{M{g}^{2+}}+\underset{2s}{2O{H}^{-}}4s^3=32.0\times {10}^{-12}s=2.0\times {10}^{-4}\text{m}\therefore [O{H}^{-}]=2\times 2\times {10}^{-4}pOH=3.39pH=10.41$