Question

What will be the charge on AgI colloidal particles when it is prepared by adding small amount of AgNO₃ solution to KI solution in water ? What is responsible for the development of this charge ?

Answer 1

When silver nitrate solution is added to KI solution, the precipitated AgI adsorbs iodide ions from the dispersion medium and negatively charged colloidal solution results. Since KI is in excess, iodide ions (I^-) will be adsorbed on the surface of AgI particles thereby giving them a negative charge.