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प्रश्न
How do emulsifying agents stabilise the emulsion?
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उत्तर
Emulsifying agents stabilize the emulsion by forming an interfacial film between suspended particle and dispersion medium. For example, agar is an emulsifying agent used in food.
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संबंधित प्रश्न
Define the following with a suitable example, of each:
Multimolecular colloid
Explain micelle formation in a soap solution.
Draw labelled diagram Dialysis.
Draw labelled diagram of Bredig’s arc method.
Which of the following statements is CORRECT?
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. \[\ce{NO^-_3}\]
Mixing of two oppositely charged sols leads to ____________.
Which of the following is multimqlecular colloid?
Tyndall effect is useful ______.
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.
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(i) heating
(ii) adding more amount of dispersion medium
(iii) freezing
(iv) adding emulsifying agent
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How does the precipitation of colloidal smoke take place in Cottrell precipitator?
Why is \[\ce{Fe(OH)3}\] colloid positively charged, when prepared by adding \[\ce{FeCl3}\] to hot water?
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Which of the following electrolytes will be most effective in coagulating negative sol?
Identify the colloidal molecule containing hydrophilic head and hydrophobic tail within it.
