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प्रश्न
Draw labelled diagram of Bredig’s arc method.
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उत्तर
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संबंधित प्रश्न
Choose the correct option.
The size of colloidal particles lies between ______.
Define the term Electrophoresis.
Write Hardy-Sulze rules.
Write a note on the Tyndall effect.
What happens when a beam of light is passed through a colloidal sol.
Explain Bredig’s arc method.
Which one of the following methods is used to make platinum sol?
Mist is a colloidal solution of ____________.
Which of the following statements is CORRECT?
Tyndall effect is observed due to ____________.
Froth is a colloidal solution of ____________.
Tyndall effect is useful ______.
The movement of colloidal particles towards respective electrode under electric field is called ______.
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.
Settling down of colloidal particles to form a suspension is called ______.
Which of the following electrolytes will have maximum coagulating value for AgI/Ag+ solution?
An emulsion cannot be broken by:
(i) heating
(ii) adding more amount of dispersion medium
(iii) freezing
(iv) adding emulsifying agent
Which of the following substances will precipitate the negatively charged emulsions?
(i) \[\ce{KCl}\]
(ii) glucose
(iii) urea
(iv) \[\ce{NaCl}\]
Gelatin which is a peptide is added in icecreams. What can be its role?
Why does bleeding stop by rubbing moist alum?
Why is \[\ce{Fe(OH)3}\] colloid positively charged, when prepared by adding \[\ce{FeCl3}\] to hot water?
Match the items of Column I and Column II.
| Column I | Column II |
| (i) Butter | (a) dispersion of liquid in liquid |
| (ii) Pumice stone | (b) dispersion of solid in liquid |
| (iii) Milk | (c) dispersion of gas in solid |
| (iv) Paints | (d) dispersion of liquid in solid |
The coagulation of 200 ML of position sol took place when 0.73 HCL was added to its without changing the volume much. The flocculation value of HCL for the colloid is.
The size of a raw mango shrinks to a much smaller size when kept in a concentrated salt solution. Which one of the following processes can explain this?
Smoke is an example of ______.
Van Arkel's method of purification of metals involves converting the metal to a ______.
Identify positively charged sol from following.
