Question

A solution containing a mixture of 0.05 M NaCI and 0.05 M Nal is taken. ($K_{sp}$ of $AgCl={10}^{-10}$ and $K_{sp}$ of $AgI=4\times {10}^{-16}$). When $AgN{O}_3$ is added to such a solution

• A. The concentration of $A{g}^{\oplus }$ required to precipitate $C{I}^{⊝}$ is $2\times {10}^{-9}mol{L}^{-1}$
• B. The concentration of $A{g}^{\oplus }$ required to precipitate $I^{⊝}$ is $8\times {10}^{-15}mol{L}^{-1}$
• C. AgCI and AgI will be precipitate together
• D. First AgI will be precipitated

Answer 1

Answer: (A), (B), (D)

The correct options are
A The concentration of $A{g}^{\oplus }$ required to precipitate $C{I}^{⊝}$ is $2\times {10}^{-9}mol{L}^{-1}$
B The concentration of $A{g}^{\oplus }$ required to precipitate $I^{⊝}$ is $8\times {10}^{-15}mol{L}^{-1}$
D First AgI will be precipitated

According to given data, $\left[A{g}^{+}\right]$ needed for precipitation of

$AgCl=\frac{{10}^{-10}}{5\times {10}^{-2}}=2\times {10}^{-9}M$

$AgI=\frac{4\times {10}^{-16}}{5\times {10}^{-2}}=8\times {10}^{-15}M$

Thus, minimum $\left[A{g}^{+}\right]$ required is for $AgI$ and so it will be precipitated first.