Question

The solubility product of $A_2{X}_3$ is $1.08\times 10^{-23}$. Its solubility will be

• A. $1.0\times 10^{-3}M$
• B. $1.0\times 10^{-4}M$
• C. $1.0\times 10^{-5}M$
• D. $1.0\times 10^{-6}M$

Answer 1

Answer: (C)

$A_2{X}_3\rightleftharpoons 2A^{+3}+3X^{-2}$
$Ksp={\left[A^{+3}\right]}^2{\left[X^{-2}\right]}^3$
$=(2S{)}^2(3S{)}^3=108S^5$
$S=\frac{Ks{p}^{1/5}}{108}=\frac{1.08\times 10^{-231/5}}{108}$
$S={\left[10^{-25}\right]}^{1/5}=10^{-5}$