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.
a) When beam of light passed through a colloidal solution of As2S3. the path of the light become visible beacuse of the tyndall effect.
b) When freshly precipitated Fe(OH)3 is shaken with little amount of dilute solution of NaCl (electrolyte).
Peptization process take place by converting the Fe(OH)3 into colloidal solution.
As ferric hydroxide Fe(OH)3 is positively charged sol it gets coagulated by Cl- ion released by NaCl
c)The movement of colloidal particles under an applied electric potential is called electrophoresis. Positively charged particles move towards the cathode while negatively charged particles move towards the anode.
Short Answer TypeLong Answer TypeIllustrate with example:
(i) Lyophilic and Lyophobic sols.
(ii) Multimolecular and macromolecular colloids.
(iii) Homogeneous and Heterogeneous catalysis.
Short Answer TypeLong Answer Type
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