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प्रश्न
Why does leather get hardened after tanning?
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उत्तर
Animal skin is colloidal, in nature and carries positive charge. Tannin is a negatively charged colloidal solution. When leather is soaked in tannin, mutual coagulation of the two takes place and leather gets hardened.
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संबंधित प्रश्न
Define the following term:
Zeta potential
Define the following terms: Associated colloids
Give reasons for the following observations:
Brownian movement provides stability to the colloidal solution.
What modification can you suggest in the Hardy-Schulze law?
Explain what is observed when an electrolyte NaCl is added to hydrated ferric oxide sol.
Explain what is observed when an electric current is passed through a colloidal sol?
What happens when a freshly prepared precipitate of Fe(OH)3 is shaken with a small amount of FeCl3 solution?
A colloidal sol is prepared by the given method in the figure. What is the charge on hydrated ferric oxide colloidal particles formed in the test tube? How is the sol represented?
Which of the following will show Tyndall effect?
How does it become possible to cause artificial rain by spraying silver iodide on the clouds?
Match the statement given in Column I with the phenomenon given in Column II.
| Column I | Column II |
| (i) Dispersion medium moves in an electric field | (a) Osmosis |
| (ii) Solvent molecules pass through semi permeable membrane towards solvent side |
(b) Electrophoresis |
| (iii) Movement of charged colloidal particles under the influence of applied electric potential towards oppositely charged electrodes |
(c) Electroosmosis |
| (iv) Solvent molecules pass through semi permeable membranes towards solution side |
(d) Reverse osmosis |
Assertion: An ordinary filter paper impregnated with collodion solution stops the flow of colloidal particles.
Reason: Pore size of the filter paper becomes more than the size of colloidal particle.
Assertion: Coagulation power of Al3+ is more than Na+.
Reason: Greater the valency of the flocculating ion added, greater is its power to cause precipitation (Hardy Schulze rule).
What is common in aqua sols and solid aerosols? How do they differ?
Gold number is associated with:-
Define coagulation.
State the Hardy-Schulze rule.
