Long Answer Type(a) Which will absorb more gas, a lump of charcoal or its powder and why?
(b) Describe the preparation of the following colloidal solutions. Name the method used in each case (i) silver sol, (ii) sulphur sol.
Explain What is observed when:
(a) A beam of light is passed through a colloidal solution of As2S3
(b) An electrolyte (NaCl) is added to ferric hydroxide sol.
(c) An electric current is passed through a colloidal solution.
Short Answer TypeLong Answer TypeIllustrate with example:
(i) Lyophilic and Lyophobic sols.
(ii) Multimolecular and macromolecular colloids.
(iii) Homogeneous and Heterogeneous catalysis.
Short Answer Type| MULTIMOLECULAR COLLOIDS | MACROMOLECULAR COLLOIDS | ACCOCIATED COLLOIDS |
| They are formed by the aggregate of a large number of atoms or molecules which generally have diameters less than 1nm, e.g. Sols of gold, sulpher etc. | They are molecules of large size e.g. polymers like rubber, nylon, starch. | They are formed by of aggregation of a large number of ions in concentrated solution e.g. soap sol. |
| Their molecular masses are not very high. | They have high molecular masses. | Their molecular masses are generally high. |
| Their atoms or molecules are held together by weak vander Waal’s forces. | Due to long chain, the vander Waal’s forces holding them are comparatively stronger. | Higher is the concentration; greater are the vander Waal’s forces. |
| They usually have lyophilic character. | They usually have lyophobic character. | Their molecules contain both lyophobic and lyophilic characters |
Long Answer Type
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