Question

Solubility of ${As}_2{S}_3$ in aqueous solution is $Smol$ $L^{-1}$. Its solubility product is $108S^n$. What will be the value of $n$?

Answer 1

Let the solubility be $S.$

${As}_2{S}_3\leftrightharpoons 2A{s}^{3+}+3S^{2-}2S3S$

Solubility product is

$K_{sp}=[A{s}^{3+}{]}^2\times [S^{2-}{]}^3$

Let $\left[{As}_2{S}_3\right]=S,\left[A{s}^{3+}\right]=2S,\left[S^{2-}\right]=3SKsp=(2S{)}^2\times (3S{)}^3=4S^2\times 27S^3=108S^5$

$n=5$