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प्रश्न
Explain Electrophoresis diagramatically.
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उत्तर
Electrophoresis set up is shown in the diagram below:
- The diagram shows a U tube set up in which two platinum electrodes are dipped in a colloidal solution.
- When an electric potential is applied across two electrodes, colloidal particles move towards one or other electrode.
- The movement of colloidal particles under an applied electric potential is called electrophoresis.
- Positively charged particles move towards the cathode while negatively charged particles migrate towards the anode and get deposited on the respective electrode.
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संबंधित प्रश्न
Distinguish between lyophobic and lyophilic sols.
Write a note on Brownian motion.
Write a note on Types of emulsion.
What happens when a beam of light is passed through a colloidal sol.
Explain Bredig’s arc method.
Draw labelled diagram Tyndall effect.
Draw labelled diagram of Bredig’s arc method.
Froth and whipped cream are examples of ____________.
Which one of the following methods is used to make platinum sol?
Identify the CORRECT statements from the following.
i. The colour of colloidal dispersion depends on size of colloidal particles.
ii. Tyndall effect is used to distinguish between colloidal dispersion and true solution.
iii. Eosin and congo red are examples of negatively charged sols.
In coagulation of positively charged ferric hydroxide sol, the most and least effective ions are ____________ and ____________ respectively.
Which of the following statements is CORRECT?
The precipitation power of an electrolyte increases with ______.
Which of the following is NOT true for lyophilic colloids?
Smoke is an example of ____________.
Which of the following is multimqlecular colloid?
In which of the following sols there is low affinity between dispersed phase and dispersion medium?
Some colloids are stable by their nature, i.e., gels, alloys, and solid foams. Gelatin and jellies are two common examples of a gel. The solid and liquid phases in a gel are interdispersed with both phases being continuous. In most systems, the major factor influencing the stability is the charge on the colloidal particles. If a particular ion is preferentially adsorbed on the surface of the particles, the particles in suspension will repel each other, thereby preventing the formation of aggregates that are larger than colloidal dimensions. The ion can be either positive or negative depending on the particular colloidal system, i.e., air bubbles accumulate negative ions, sulphur particles have a net negative charge in a sulphur sol, and the particles in a metal hydroxide sol are positively charged. Accumulation of charge on a surface is not an unusual phenomenon-dust is attracted to furniture surfaces by electrostatic forces. When salts are added to lyophobic colloidal systems the colloidal particles begin to form larger aggregates and a sediment forms as they settle. This phenomenon is called flocculation, and the suspension can be referred to as flocculated, or colloidally unstable. If the salt is removed, the suspension can usually be restored to its original state; this process is called deflocculation or peptization. The original and restored colloidal systems are called deflocculated, peptized, or stable sols.
Why does a small amount of salt have such a dramatic effect on the stability of a lyophobic colloidal system? The answer lies in an understanding of the attractive and repulsive forces that exist between colloidal particles. Van der Waals forces are responsible for the attractions, while the repulsive forces are due to the surface charge on the particles. In a stable colloid, the repulsive forces are of greater magnitude than the attractive forces. The magnitude of the electrical repulsion is diminished by addition of ionized salt, which allows the dispersed particles to aggregate and flocculate. River deltas provide an example of this behaviour. A delta is formed at the mouth of a river because the colloidal clay particles are flocculated when the freshwater mixes with the salt water of the ocean.
Colloidal solutions are stable due to ______.
Which of the following substances will precipitate the negatively charged emulsions?
(i) \[\ce{KCl}\]
(ii) glucose
(iii) urea
(iv) \[\ce{NaCl}\]
How does the precipitation of colloidal smoke take place in Cottrell precipitator?
On the basis of Hardy-Schulze rule explain why the coagulating power of phosphate is higher than chloride.
Cloud is an example of
For coagulating 200 ml of arsenious sulphide sol, 10 ml of 1 m NaCl solution is required find out the flocculation value of NaCl.
Which of the following substances will precipitate the negatively charge emulsion
The migration of dispersion medium under the influence of an electric potential is called ______.
Blood may be purified by ______.
Van Arkel's method of purification of metals involves converting the metal to a ______.
Starch is an example of which of the following type of colloid?
