Question

At ${25}^{o}C$, the solubility product of salt of ${MX}_2$ type is $3.2\times {10}^{-8}$ in water. The solubility (in mol/L) of ${MX}_2$ in water at the same temperature will be:

• A. $1.2\times {10}^{-3}$
• B. $2\times {10}^{-3}$
• C. $3.2\times {10}^{-3}$
• D. $1.75\times {10}^{-3}$

Answer 1

Answer: (B)

$2\times {10}^{-3}$

For ${MX}_2$ type salt:

Solubility product, $K_{sp}=4S^3$

$3.2\times {10}^{-8}=4S^3$

or, $S=\sqrt[3]{3\frac{3.2\times {10}^{-8}}{4}}=2\times {10}^{-3}mol/L$