Question

The solubility product, $K_{Sp}$, of sparingly soluble salt $MX$ at ${25}^{o}C$ is $2.5\times {10}^{-9}$. The solubility of the salt in $mol$ $L^{-1}$ at this temperature is:

• A. $1\times {10}^{-14}$
• B. $5\times {10}^{-8}$
• C. $1.25\times {10}^{-9}$
• D. $5\times {10}^{-5}$

Answer 1

The correct option is D $5\times {10}^{-5}$

$MX\rightleftharpoons M^{+}+X^{-}$

$S$ $S$ $S$

Let the solubility of $MX$ be $S$ ${molL}^{-1}$.

$\therefore$ $K_{sp}=\left[M^{+}\right]\left[X^{-}\right]=S^2$

$\therefore$ $S=\sqrt{K_{sp}}=\sqrt{2.5\times {10}^{-9}}=5\times {10}^{-5}$