Question

The solubility product ($K_{sp}$) of $AgCl$ is $1.8\times {10}^{-10}$. Precipitation of $AgCl$ will occur only when equal volumes of solutions of:

• A. ${10}^{-4}M{Ag}^{+}$ and ${10}^{-4}M{Cl}^{-}$ are mixed
• B. ${10}^{-7}M{Ag}^{+}$ and ${10}^{-7}M{Cl}^{-}$ are mixed
• C. ${10}^{-5}M{Ag}^{+}$ and ${10}^{-5}M{Cl}^{-}$ are mixed
• D. ${10}^{-10}M{Ag}^{+}$ and ${10}^{-10}M{Cl}^{-}$ are mixed

Answer 1

The correct option is A ${10}^{-4}M{Ag}^{+}$ and ${10}^{-4}M{Cl}^{-}$ are mixed

Precipitation will occur when $Q_{sp}>K_{sp}(1.8\times {10}^{-10})$.

$Q_{sp}=\left[A{g}^{+}\right]\left[C{l}^{-}\right]={10}^{-4}\times {10}^{-4}={10}^{-8}>1.8\times {10}^{-10}$