Question

If the solubility product of $CuS$ is $6\times 10^{-16}$, the maximum molarity of $CuS$ in aqueous solution will be

• A. $3.45\times 10^{-5}mo{l}^{-1}$
• B. $2.45\times 10^{-8}mo{l}^{-1}$
• C. $2.45\times 10^{8}mo{l}^{-1}$
• D. $3.45\times 10^{5}mo{l}^{-1}$

Answer 1

Answer: (B)

Maximum molarity of $CuS$ in aqueous solution = Solubility of $CuS$ in mol $L^{-1}$
If $S$ is the solubility of $CuS$ in mol $L^{-1}$, then
$CuS\rightleftharpoons C{u}^{2+}+S^{2-},K_{sp}=[C{u}^{2+}][S^{2-}=S\times S=S^2$
$\therefore S^2=6\times 10^{-16}$
or $S=\sqrt{6\times 10^{-16}}=2.45\times 10^{-8}mol{L}^{-1}$