Question

The solubility of $A_2{X}_5$ is $xmol{dm}^{-3}$. Its solubility product is:

• A. $36x^6$
• B. $64\times {10}^4{x}^7$
• C. $126x^7$
• D. $1.25\times {10}^4{x}^7$

Answer 1

The correct option is D $1.25\times {10}^4{x}^7$

Let the solubility be $S.$

${As}_2{X}_3\leftrightharpoons 2A{s}^{5+}+5X^{2-}2S5S$

Solubility product is

$K_{sp}=[A{s}^{5+}{]}^2\times [S^{2-}{]}^5$

Let $\left[{As}_2{S}_5\right]=S,\left[A{s}^{5+}\right]=2S,\left[S^{2-}\right]=5SKsp=(2S{)}^2\times (5S{)}^5=4S^2\times 3125S^5=12500S^7$