471.

Which mixture of the solutions will lead to the formation of negatively charged colloidal [Agl]l– sol ?

• 50 mL of 1 M AgNO₃ + 50 mL of 2 M KI

• 50 mL of 2 M AgNO₃ + 50 mL of 1.5 M KI

• 50 mL of 0.1M M AgNO₃ + 50 mL of 0.1 M KI

• 50 mL of 1 M AgNO₃ + 50 mL of 1.5 M KI

Generally charge present on the colloid is due to adsorption of common ion from dispersion medium. Millimole of KI is maximum in option (2) (50 × 2 = 100) so act as solvent and anion I^– is adsorbed by the colloid AgI formed

$$\begin{gathered} {\mathrm{AgNO}}_3 + \mathrm{KI} \to \mathrm{AgI} + {\mathrm{KNO}}_3 \\ \mathrm{D}.\mathrm{P} \underset{\left(\mathrm{excess}\right)}{ \mathrm{D}.\mathrm{M} } \underset{\mathrm{colloid}}{ \mathrm{Negative} \mathrm{charged}} \end{gathered}$$