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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 terms: Associated colloids
Define the following term : Brownian movement
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 the terms Coagulation
Answer the following question.
Why are medicines more effective in the colloidal state?
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 solution represented?
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: 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).
Give reason for the following:
Lyophilic colloidal solutions are more stable than lyophobic colloidal solutions.
What is Gold number?
Tyndall effect is observed in
Which of the following is used for removing change on colloidal solution?
Gold number of protective colloids A, Band Dare 0.50, 0.01 and 0.10 and 0.005. The correct order of their protecting power is
What is electrophoresis?
Which of the following is a correct statement?
Coagulation value of the electrolytes AlCl3 and NaCl for As2S3 sol are 0.093 and 52 respectively. The No. of times AlCl3 has greater coagulating power than NaCl is ______.
In order to cause coagulation of 100 ml Arsenious sulphide sol 111.7 mg of 2 M NaCl solution is used, the coagulation value of NaCl will be ______.
6.84 g Al2(SO4)3 is needed to coagulate 2.5 L of As2S3 sol completely in 2.0 hrs. The coagulation value of Al2 (SO4)3 is ______.
