Advertisements
Advertisements
Question
Why does leather get hardened after tanning?
Advertisements
Solution
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.
APPEARS IN
RELATED QUESTIONS
What is the reason for the stability of colloidal sols?
Give reasons for the following observations:
Brownian movement provides stability to the colloidal solution.
Give reasons for the following observations: Leather gets hardened after tanning.
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 persistent dialysis of a colloidal solution is carried out?
Which of the following will show Tyndall effect?
Which of the following statements are correct?
(i) Mixing two oppositely charged sols neutralises their charges and stabilises the colloid.
(ii) Presence of equal and similar charges on colloidal particles provides stability to the colloids.
(iii) Any amount of dispersed liquid can be added to emulsion without destabilising it.
(iv) Brownian movement stabilises sols.
What happens when a lyophilic sol is added to a lyophobic sol?
(i) Lyophobic sol is protected.
(ii) Lyophilic sol is protected.
(iii) Film of lyophilic sol is formed over lyophobic sol.
(iv) Film of lyophobic sol is formed over lyophilic sol.
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: Colloidal solutions do not show brownian motion.
Reason: Brownian motion is responsible for stability of sols.
Give reason for the following:
Lyophilic colloidal solutions are more stable than lyophobic colloidal solutions.
Which of the following is used for removing change on colloidal solution?
Gold number is associated with:-
Define coagulation.
Define the following term:
Coagulation
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:
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 ______.
