# If the solubility product of $CuS$ is $6 \times 10^{-6}$ calculate the maximum molarity of $CuS$ is aqueous solution

Solution :
Maximum molarity of $CuS$ in aqueous = solubility of $CuS$ in $mol ^{-1}$.
If $S$ is the solubility of $CuS$ in $mol^{-1}$ then
$Cus \to Cu^{2+} + S^{2+}$
$K_{sp}= [cu^{2+}] [S^{2-}]$
$\qquad= S \times S =S^2$
$S^2= 6 \times 10^{-16}$ or
$S= \sqrt{ 6 \times 10^{-6}}=2.45 \times 10^{-8}mol L^{-1}$
Maximum molarity of $CuS$ in aqueous solution $= 2.45 \times 10^{-8} mol L^{-1}$
edited Dec 2, 2016