(1) What is meant by solvation of colloidal particle??
(1) Each particle of colloids is coated with a monomolecular layer of the dispersion media. This called solvation of colloids. Dispersed particles of intrinsic shape and some polymer molecules entrap additional molecules of the dispersion media resulting in higher solvation of the colloid system. Due to solvation colloids are more viscous than the dispersion media.
(2) The process of protecting a lyophobic sol from being coagulated (precipitated) on addition of an electrolyte by the use of a lyophilic colloids is called protection and the lyophilic colloid used for purpose is called a protective colloid.
Gold number is a term used in colloidal chemistry. It is defined as the minimum amount of lyophilic colloid in milligrams which prevents the coagulation of 10 ml gold sol against 1 ml of 10% NaCl solution. Smaller the gold number of a protective colloid, the greater is its protective action.
(3) Lyophilic colloids are highly solvated as well as charged. The charge usually is a result of ionization.
Most of the gums used in pharmacy to make colloids like acacia are negatively charged due to the carboxyllic or sulfate groups on the carbohydrate polymer.