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प्रश्न
Comment on the statement that “colloid is not a substance but a state of substance”.
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उत्तर
Common salt (a typical crystalloid in an aqueous medium) behaves as a colloid in a benzene medium. Hence, we can say that a colloidal substance does not represent a separate class of substances. When the size of the solute particle lies between 1 nm and 1000 nm, it behaves as a colloid.
Hence, we can say that a colloid is not a substance but a state of the substance, which is dependent on the size of the particle. A colloidal state is intermediate between a true solution and a suspension.
संबंधित प्रश्न
Write one difference in Multimolecular colloid and Associated colloid
Define the following with a suitable example, of each:
Multimolecular colloid
Define the following with a suitable example, of each:
Gel
Froth and whipped cream are examples of ____________.
Mist is a colloidal solution of ____________.
Which of the following statements is CORRECT?
Which of the following is an example of liquid-liquid system?
The order of coagulating power of following ions in the coagulation of a positive sol is:
i. \[\ce{PO^{3-}_4}\]
ii. \[\ce{SO^{2-}_4}\]
iii. \[\ce{[Fe(CN)6]^{4-}}\]
iv. \[\ce{NO^-_3}\]
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Which of the following is multimqlecular colloid?
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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 ______.
Freshly prepared precipitate sometimes gets converted to colloidal solution by ______.
Which of the following process is responsible for the formation of delta at a place where rivers meet the sea?
Gelatin which is a peptide is added in icecreams. What can be its role?
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.
Smoke is an example of ______.
Identify positively charged sol from following.
