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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
Give reasons for the following observations: Leather gets hardened after tanning.
Explain what is observed when a beam of light is passed through a colloidal sol.
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?
Explain the terms Dialysis
Explain the term Tyndall effect.
What happens when a freshly prepared precipitate of Fe(OH)3 is shaken with a small amount of FeCl3 solution?
What happens when an emulsion is centrifuged?
The values of colligative properties of colloidal solution are of small order in comparison to those shown by true solutions of same concentration because of colloidal particles ______.
Which phenomenon occurs when an electric field is applied to a colloidal solution and electrophoresis is prevented?
(i) Reverse osmosis takes place.
(ii) Electroosmosis takes place.
(iii) Dispersion medium begins to move.
(iv) Dispersion medium becomes stationary.
Why do we add alum to purify water?
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 Gold number?
Which of the following is used for removing change on colloidal solution?
Define coagulation.
Define the following term:
Coagulation
Why a negatively charged sol is obtained when AgNO3 solution is added to KI solution?
The conditions given below are in the context of observing Tyndall effect in colloidal solutions:
- The diameter of the colloidal particles is comparable to the wavelength of light used.
- The diameter of the colloidal particles is much smaller than the wavelength of light used.
- The diameter of the colloidal particles is much larger than the wavelength of light used.
- The refractive indices of the dispersed phase and the dispersion medium are comparable.
- The dispersed phase has a very different refractive index from the dispersion medium.
Choose the most appropriate conditions from the options given below:
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 ______.
