Long Answer Type
Short Answer TypeLong Answer TypeAnswer:
(i) Based on physical states of components. Depending upon whether the dispersed phase and the dispersion medium are solids, liquids or gases, eight types of colloidal system are possible. The examples of the various type of colloids along with their typical names are given following:
|
Dispersed |
Dispersion |
Type of |
Examples |
|
phase |
medium |
colloid |
|
|
Solid Solid Solid Liquid Liquid Liquid Gas Gases |
Solid Liquid Gas Solid Liquid Gas Solid Liquid |
Solid Sol Sol Aerosol Gel Emulsion Aerosol Solid sol Foam |
Some coloured glasses and gem stones. Paints, cell fluids Smoke, dust Cheese, butter, jellies. Milk, hair cream Fog, mist, cloud, insecticide sprays. Pumice stone, form rubber Froth, whipped cream,soap-lather. |
(ii) Nature of dispersion medium. Depending upon the type of the particles of the dispersed pahse, colloids are classified as multimolecular, macromolecular and associated colloids.
Multimolecular colloids. The colloids in which the colloidal particles consists of aggregate of atoms or small molecules with diameters of less than 1 mm and called multimolecular colloids e.g., sulphur sol.
Macro molecular colloids. Macro molecules have large molecular masses. These on dissolution in a suitable solvent form a solution in which the size of the macromolecules may be in the colloidal range. Such systems are called macromolecular colloids. Example: proteins, starch and cellulose.
Associated colloids. There are some substances which at low concentrations behave as normal, strong electrolytes but at higher concentrations exhibit colloidal behaviour due to the formation of aggregated particles. The aggregated particles thus formed are called micelles. These are also known as associated colloids.
(iii) Interaction between dispersed phase and dispersion medium. Depending upon the nature of interaction between the dispersed phase and the dispersion medium, colloidal sols are divided into two categories, namely, lyophilic and lyophobic.
Lyophilic colloids. The colloidal solution in which the particles of the dispersed phase have a greater affinity for the dispersion medium are called lyophilic colloids. The common example of lyophilic colloids are glue, gelatin, starch, protein, rubber, etc.
Lyophobic colloids. The colloidal solutions in which the particles of the dispersed phase have no affinity or love rather have hatred for the dispersion medium are called lyophobic colloids.
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