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प्रश्न
Draw labelled diagram of Bredig’s arc method.
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उत्तर
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संबंधित प्रश्न
Comment on the statement that “colloid is not a substance but a state of substance”.
Write one difference in Multimolecular colloid and Associated colloid
Choose the correct option.
The size of colloidal particles lies between ______.
Write a note on Types of emulsion.
What are the applications of Electrophoresis?
Explain micelle formation in a soap solution.
Which type of colloid is formed on the dissolution of soap in water?
Froth and whipped cream are examples of ____________.
Which one of the following methods is used to make platinum sol?
Identify the CORRECT statement.
Which of the following statements is CORRECT?
Which of the following is an example of liquid-liquid system?
Which of the following is NOT true for lyophilic colloids?
Mixing of two oppositely charged sols leads to ____________.
Tyndall effect is observed due to ____________.
Smoke is an example of ____________.
Froth is a colloidal solution of ____________.
Which of the following ionic species has highest precipitating power?
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 substances will precipitate the negatively charged emulsions?
(i) \[\ce{KCl}\]
(ii) glucose
(iii) urea
(iv) \[\ce{NaCl}\]
A colloid is formed by adding \[\ce{FeCl3}\] in excess of hot water. What will happen if excess sodium chloride is added to this colloid?
On the basis of Hardy-Schulze rule explain why the coagulating power of phosphate is higher than chloride.
Cloud is an example of
Which of the following substances will precipitate the negatively charge emulsion
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?
The migration of dispersion medium under the influence of an electric potential is called ______.
Identify positively charged sol from following.
