Question

Solubility product (KSP) of salts of types $MX,M{X}_2$ and $M_{3}X$ at temperature T are $4\times {10}^{-8},3.2\times {10}^{-14}$ and $2.7\times {10}^{-15}$ respectively, solubility of salts at temperature T are in order

• A. $MX>M{X}_2>M_{3}X$
• B. $M_{3}X>M{X}_2>MX$
• C. $M{X}_2>M_{3}X>MX$
• D. $MX>M_{3}X>M{X}_2$

Answer 1

The correct option is D $MX>M_{3}X>M{X}_2$

$MX\rightleftharpoons \underset{s}{M^{+}}+\underset{s}{X^{-}}$
$K_{sp}=s^2,s=\sqrt{K_{sp}}$
$s=2\times {10}^{-4}$
$M{X}_2\rightleftharpoons \underset{s}{M^{+2}}+2\underset{2s}{X^{-}}$
$K_{sp}=4s^3;s=\sqrt[3]{3\frac{K_{sp}}{4}}s=2\times {10}^{-5}$
$M_{3}X\rightleftharpoons 2\underset{3s}{M^{+}}+\underset{s}{X^{-3}}$
$K_{sp}=27x^4;s=\sqrt[4]{4\frac{K_{sp}}{27}}=1\times {10}^{-4}$