Question

How is the exchange of solvent useful in the preparation of a colloidal solution? Explain with an example.

Answer 1

Exchange of solvent is a useful method for preparing colloidal solutions. In this method, a true solution of a substance is prepared in a solvent in which it is soluble, and then this solution is poured into another solvent in which the substance is insoluble, but the two solvents are mutually miscible. This results in the formation of colloidal particles of the substance, which can be dispersed in the second solvent, forming a colloidal sol.

Example: Sulfur dissolves in alcohol but not in water. When an alcoholic sulfur solution is poured into water with constant stirring, a colloidal sulfur solution is formed.

This method is especially effective for preparing colloidal sols for substances like sulfur and phosphorus.