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Explain types of colloids |
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Answer» Colloids are classified into 7 groups:•Sol•Solid sol•Aerosol•Emulsion•Foam•Solid Foam•Gel A colloid is primarily a heterogeneous mixture in which the minute particles of one substance are dispersed in another substance, called the dispersion medium.Colloids can be classified according to different properties of the dispersed phase and medium.Firstly, based on the types of particles of the dispersed phase, colloids can be classified as:\tMultimolecular colloids: When the dissolution of smaller molecules of substance or a large number of atoms takes place, they combine to form a species whose size is in the range of colloidal size. The species formed is known as the multimolecular colloids. For example, Sulphur solution contains particles which have thousands of S8.\tMacromolecular colloids: In this type of colloids, the macromolecules form a solution with a suitable solvent. The size of the particles of this macromolecular solution lies in the range of colloidal particles size. Thus this solution is also known as the macromolecular colloids. The colloids formed here are similar to that of the actual solution in many respects and are very stable. Example: Starch, proteins, enzymes, and cellulose are the naturally occurring macromolecular colloids whereas polyethene, synthetic rubber, etc. are the synthetic macromolecules.\tAssociated colloids: Some substances act as a strong electrolyte when they are in low concentrations, but they react as colloidal sols when they are in high concentration. In higher concentration, particles aggregate showing a colloidal behaviour. These aggregated particles are known as the micelles. They are also known as the associated colloids. The formation of the micelles occurs above a particular temperature called the Kraft temperature (Tk) and also above a specific concentration called the critical micelle concentration. These colloids can be reverted by diluting it. Examples of some associated colloids are soaps and synthetic detergents. |
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