Question

The solubility of $Ca(OH{)}_2$ in water is:

[Given: The solubility product of $Ca(OH{)}_2$ in water = $5.5\times {10}^{-6},{1.375}^{\frac{1}{3}}=1.11$]

• A. $1.11\times {10}^{-6}$
• B. $1.77\times {10}^{-6}$
• C. $1.77\times {10}^{-2}$
• D. $1.11\times {10}^{-2}$

Answer 1

The correct option is D $1.11\times {10}^{-2}$

$\begin{array}{ccccc}Ca(OH{)}_2& \rightleftharpoons & C{a}^{+2}& +& 2O{H}^{-}\\ & & S& & \left(2S\right)\end{array}$
The solubility product is
$S(2S{)}^2=5.5\times {10}^{-6}$
$\Rightarrow 4S^3=5.5\times {10}^{-6}$

$\Rightarrow S=(1.37{)}^{\frac{1}{3}}\times {10}^{-2}$

$\Rightarrow S=1.11\times {10}^{-2}$