Explain the following terms:
(i) Electrophoresis (ii) Coagulation (iii) Dialysis (iv) Tyndall effect.

Explanation

(i) Electrophoresis : The movement of colloidal particles towards oppositely charged electrodes in the presence of an electric field is called electrophoresis. If this movement is towards cathode, the term used in cataphoresis.
(ii) Coagulation : The formation of aggregates or precipitates of colloidal particles by addition of a suitable electrolyte is called coagulation
(iii) Dialysis : The process of removing a dissolved substance from the colloidal solution by means of diffusion through a suitable membrane is called dialysis. Colloidal particles are prevented from passing through this membrane due to their bigger size.
(iv) Tyndall effect: When a beam of light is passed through a colloidal solution and the solution is viewed at right angles to the passage of light, they show a mild to strong opalescence, i.e., the path of beam of light is illuminated. This phenomenon is called Tyndall effect. This is cause due to scattering of light by colloidal particles.