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Explain about protective action of colloid. |
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Answer» Solution : (i) Lyophobic sols are precipitated readily even with SMALL AMOUNT of electrolytes. But they are stabilised by the addition of small amount of lyophillic colloid. (ii) A small amount of gelatine sol is added to gold sol to protect gold sol. (III) Gold number is a measure of protecting power of a colloid. Gold number is defined as the number of MILLIGRAMS of hydrophillic colloid that will just prevent the precipitation of 10ml of gold sol on the addition of 1 ml of 10% NaCl solution. SMALLER the gold number, greater the protective power. |
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