Question

The solubility of $Ca ( OH )_{2}$ in water is [Given : The solubility product of $Ca ( OH )_{2}$ in water $\left.=5.5 \times 10^{-6}\right]$

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

Answer 1

Answer: (C)

$Ca(OH)_2 \rightleftharpoons Cs^{2+}\underset{S}{(aq)} + 2OH^- \underset{2S}{(aq)}$

$k_{sp} = s(2s)^2 \Rightarrow 5.5 \times 10^{-6} = 4S^3$

$\Rightarrow s = \left(\frac{5.5}{4}\right)^{\frac{1}{3}} \times 10^{-2} = 1.11 \times 10^{-2}$