The process of removing dissolved substance from a colloidal solution by means of diffusion through a suitable membrane is termed as…………..

Options

A. dialysis
B. pyrolysis
C. photolysis
D. hydrolysis

Answer

A

Explanation

The colloidal sols prepared by various methods are impure as they generally contain excessive amount of electroytes and some other soluble impurities. While the presence of traces of electrolytes is essential for the stability of the colloidal solution, larger quantities coagulate it. Thus it is necessary to reduce the concentration of these soluble impurities to a requisite minimum.
The process used for reducing the amount of impurities to a requisite minimum is known as purification of colloidal solution.
Dialysis is a very important method of removal of soluble impurities from sols by a suitable called semi permeable member. Since particles of true solutions (ions or small molecules) can pass through animal membrane (bladder) or parchment paper or cellophane sheet but not the colloidal particles, the membrane can be used for dialysis. The apparatus used for this purpose is called dialyser. A bag made up of such a membrane is filled with the impure colloidal solution and is then suspended in a vessel through which fresh water is continously flowing. The extra electrolyte particles (ions and molecules) pass out leaving behind the colloidal sol.