How are colloids classified on the basis of (i) physical states of components (ii) nature of dispersed phase and (iii) interaction between dispersed phase and dispersion medium?
The classification of colloids on the basis of (i) physical states of components: On the basis of physical states of the dispersed phase and dispersion medium, the colloidal solutions classified into eight types of colloidal systems (ii) Nature of dispersed phase and dispersion medium: Colloids are classified into following. (i) Alcosol It is a colloidal solution of a solid (dispersed phase) in alcohol (Dispersion medium). (ii) Aerosol It is a colloidal solution of a liquid (dispersed phase) in gas (Dispersion medium). Example includes fog. (iii) Hydrosol It is a colloidal solution of a solid (dispersed phase) in water (Dispersion medium). (iv) Benzosol : It is a colloidal solution with benzene as dispersion medium. (iii) Interaction between dispersed phase and dispersion medium: Colloids are classified into lyophilic sols and lyophobic sols. In lyophilic sols, the dispersed phase particles have great affinity (or love) for the dispersion medium. These sols are reversible. Examples include gum, gelatin, starch, proteins and rubber etc. In lyophobic sols, the dispersed phase particles have no affinity (or love) for the dispersion medium. These sols are irreversible. Examples include solutions of metals such as gold and silver, metal hydroxides and metal sulphides. The hydrophobic sols are less stable and easily coagulated than hydrophilic sols because, the stability of hydrophobic sols is due to charge only and the stability of hydrophilic sols is due to charge and solvation/ hydration.
