Question

What is the value of $pH$ of saturated solution of $Mg\left(\right.OH\left(\left.\right)_{2}?\left(\right.K_{sp}$ for $Mg\left(\right.OH\left(\left.\right)_{2}$ is $8.9\times 10^{- 12}$ )

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

Answer 1

Answer: (C)

$Mg\left(\right.OH\left(\left.\right)_{2}\rightleftharpoons\underset{s}{\left(Mg\right)^{2 +}}+\underset{2 s}{2 \left(OH\right)^{-}}$
$4s^{3}=8.9\times 10^{- 12}$
$s=1.3\times 10^{- 4}m$
$\therefore \left[\right.OH\left]\right.=2\times 1.305\times 10^{- 4}$
$pOH=3.58832$
$pH=10.4168$ .