Question

Which mixture of the solutions will lead to the formation of negatively charged colloidal [AgI]I⁻ sol?

Options

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

• 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 0.1 M AgNO₃ + 50 mL of 0.1 M KI

Answer 1

50 mL of 1 M AgNO₃ + 50 mL of 2 M KI

Explanation:

When excess KI is used compared to AgNO₃, the colloidal AgI particles preferentially adsorb excess I⁻ ions from KI, giving them a negative charge and forming negatively charged [AgI]⁻ sol. If AgNO₃ is in excess, Ag⁺ ions adsorb, leading to positively charged sol. Higher concentration of KI compared to AgNO₃ causes preferential adsorption of iodide ions on colloidal AgI particles, making the sol negatively charged.