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Give information about applications of colloids. |
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Answer» Solution :Colloids are widely used in the industry. Following are some examples : (i) Electrical precipitation of SMOKE : Smoke is a colloidal solution of solid particles such as carbon, arsenic compounds, dust etc. in air. The smoke, before it comes out from the chimney is led through a chamber containing plates having a charge opposite to that carried by smoke particles. The particles on coming in contact with these plates lose their charge and get PRECIPITATED. The particles thus settle down on the floor of the chamber. The precipitator is called cottrell precipitator.  (ii) Purification of drinking water : The water obtained from natural sources often contains suspended impurities. Alum is added to such water to coagulate the suspended impurities and make water fit for drinking purpose. (iii) Medicines : Most of the medicines are colloidal in nature. For example, argyrol is a silver sol used as an eye lotion. Colloidal antimony is used in curing kalaazar. Colloidal gold is used for intramuscular injection. Milk of magnesia an emulsion is used for stomach disorder. Colloidal medicine are more effective because they have large surface area and are therefore easily assimilated. (iv) Tanning : Animal hides are colloidal in nature. When a hide, which has positively charged particles is soaked in tannin, which contains negatively charged colloidal particles, mutual coagulation takes place. This RESULTS in the hardening of leather. This process is termed as tanning. Chromium salts are also used in place of tannin. (v) Cleansing action of soaps and detergent : This has already been DESCRIBE in section 5.4.3. (vi) Photographic plates and films : Photographic plates or films are prepared by coating an emulsion of the light sensitive silver bromide in gelatin over glass plates or celluloid films. (VII) Rubber industry : Latex is a colloidal solution of rubber particles which are negatively charged. Rubber is obtained by coagulation of latex. (viii) Industrial products : Paints, inks, synthetic plastics, rubber, graphite lubricants, cement etc. are all colloidal solution. |
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