What is the $\mathrm{pH}$ at which $\mathrm{Mg}(\mathrm{OH})_2$ starts to precipitate from a solution containing $0.1 \mathrm{M} \mathrm{Mg}^{2+}$ ions? (Given Ksp for $\mathrm{Mg}(\mathrm{OH})_2=1.0 imes 10^{-11}$ )

Question

What is the $\mathrm{pH}$ at which $\mathrm{Mg}(\mathrm{OH})_2$ starts to precipitate from a solution containing $0.1 \mathrm{M} \mathrm{Mg}^{2+}$ ions? (Given Ksp for $\mathrm{Mg}(\mathrm{OH})_2=1.0 	imes 10^{-11}$ )

Aicharya · Accepted Answer

$\begin{aligned} & \mathrm{K}_{\mathrm{sp}}=\left(\mathrm{Mg}^{+2}ight)\left[\mathrm{OH}^{-}ight]^2 \ & 1 	imes 10^{-11}=(0.1)\left[\mathrm{OH}^{-}ight]^2 \ & \Rightarrow\left[\mathrm{OH}^{-}ight]=10^{-5} \mathrm{M} \ & \mathrm{pOH}=5 ; \mathrm{pH}=9\end{aligned}$

What is the $\mathrm{pH}$ at which $\mathrm{Mg}(\mathrm{OH})_2$ starts to precipitate from a solution…

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