Advertisements
Advertisements
प्रश्न
Why do we add alum to purify water?
Advertisements
उत्तर
River water carries negatively charged colloidal particles of clay and sand; alum \[\ce{(K2SO4Al2(SO4)3 24H2O)}\] is added to river water to coagulate the colloidal particles of clay and sand. Thus, alum helps to purify water.
APPEARS IN
संबंधित प्रश्न
Give reasons for the following observations:
Brownian movement provides stability to the colloidal solution.
Out of MgCl2 and AlCl3, which one is more effective in causing coagulation of negatively charged sol and why?
What modification can you suggest in the Hardy-Schulze law?
Explain the term Tyndall effect.
What happens when persistent dialysis of a colloidal solution is carried out?
What happens when an emulsion is centrifuged?
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?
Which of the following will show Tyndall effect?
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.
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?
The important factor in the stabilization of a colloidal solution is ______
The right option for the statement “Tyndall effect is exhibited by”, is:
Define coagulation.
