Question

On adding $AgN{O}_3$ solution into $KI$ solution, a negatively charged colloidal solution is obtained when they are in:

• A. 100 mL of 0.1 M AgNO${}_3$ + 100 mL of 0.1 M KI
• B. 100 mL of 0.1 M AgNO${}_3$ + 100 mL of 0.2 M KI
• C. 100 mL of 0.2 M AgNO${}_3$ + 100 mL of 0.1 M KI
• D. 100 mL of 0.15 M AgNO${}_3$ + 100 mL of 0.15 M KI

Answer 1

The correct option is B 100 mL of 0.1 M AgNO${}_3$ + 100 mL of 0.2 M KI

Negatively charged colloidal sol is formed when $AgN{O}_3$ is completely precipitated as $Agl$ and extra $KI$ is absorbed on $Agl$.
$A{g}^{+}+I^{-}\to Agl$
$Agl+I^{-}\to [Agl{]}^{-}$
Thus, $\left[A{g}^{+}\right]<\left[I^{-}\right]$