Question

The solubility product of a salt having general formula ${MX}_2$ in water is $4\times {10}^{-12}$. The concentration of $M^{2+}$ ions in the aqueous solution of the salt is:

• A. $4.0\times {10}^{-10}M$
• B. $1.6\times {10}^{-4}M$
• C. $1.0\times {10}^{-4}M$
• D. $2.0\times {10}^{-6}M$

Answer 1

The correct option is C $1.0\times {10}^{-4}M$

Solubility product= $4\times {10}^{-12}$

$M{X}_2\rightleftharpoons M^{2+}+2X^{-}$

$\left(s\right)$ $(2s{)}^2$

$\left(s\right)$ $4s^2$

$\left(s\right)\left(4s^2\right)$= Solubility product

$4s^3=4\times {10}^{-12}$

$\Rightarrow s^3={10}^{-12}$

$\Rightarrow s={10}^{-4}M$

Concentration of $M^{2+}$ ions $=$ $s=1\times {10}^{-4}M$