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प्रश्न
On the basis of Hardy-Schulze rule explain why the coagulating power of phosphate is higher than chloride.
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उत्तर
Minimum quantity of an electrolyte required to cause precipitation of a sol is called its coagulating value. Greater the charge on flocculating ion and smaller is the amount of electrolyte required for precipitation, higher is the coagulating power of coagulating ion (Hardy-Schulze rule).
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संबंधित प्रश्न
Comment on the statement that “colloid is not a substance but a state of substance”.
Define the following with a suitable example, of each:
Multimolecular colloid
Distinguish between lyophobic and lyophilic sols.
Identify the dispersed phase and dispersion medium in the following colloidal dispersions.
- milk
- blood
- printing ink
- fog
Write a note on Brownian motion.
Explain the term emulsion and types of emulsions.
Draw labelled diagram Dialysis.
Draw labelled diagram of Soap micelle.
In coagulation of positively charged ferric hydroxide sol, the most and least effective ions are ____________ and ____________ respectively.
Which of the following is an example of liquid-liquid system?
The precipitation power of an electrolyte increases with ______.
Mixing of two oppositely charged sols leads to ____________.
Froth is a colloidal solution of ____________.
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 ______.
A colloidal system having a solid substance as a dispersed phase and a liquid as a dispersion medium is classified as ______.
What happens when electric field is applied to colloidal solution?
How do emulsifying agents stabilise the emulsion?
Which of the following substances will precipitate the negatively charge emulsion
Blood may be purified by ______.
