Question

Solubility product for salt $A{B}_2$ is $4\times {10}^{-12}$. Calculate solubility.

• A. $1\times {10}^{-3}M$
• B. $1\times {10}^{-5}M$
• C. $1\times {10}^{-4}M$
• D. $1\times {10}^{-2}M$

Answer 1

Answer: (C)

$1\times {10}^{-4}M$

$A{B}_2=\underset{\left(S\right)}{A^{2+}}+\underset{(2S{)}^2}{2B^{-}}$

$K_{sp}=4S^3$

$S=\sqrt[3]{3\frac{K_{sp}}{4}}=\sqrt[3]{3\frac{4\times {10}^{-12}}{4}}=1\times {10}^{-4}M$