Advertisements
Advertisements
Question
Why do we add alum to purify water?
Advertisements
Solution
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
RELATED QUESTIONS
What is the reason for the stability of colloidal sols?
What modification can you suggest in the Hardy-Schulze law?
Explain what is observed when a beam of light is passed through a colloidal sol.
Explain the term Tyndall effect.
What happens when an emulsion is centrifuged?
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?
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?
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.
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.
Tyndall effect is observed in
Define coagulation.
What is electrophoresis?
Which of the following is a correct statement?
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 ______.
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 ______.
