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प्रश्न
Explain Electrophoresis diagramatically.
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उत्तर
Electrophoresis set up is shown in the diagram below:
- The diagram shows a U tube set up in which two platinum electrodes are dipped in a colloidal solution.
- When an electric potential is applied across two electrodes, colloidal particles move towards one or other electrode.
- The movement of colloidal particles under an applied electric potential is called electrophoresis.
- Positively charged particles move towards the cathode while negatively charged particles migrate towards the anode and get deposited on the respective electrode.
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संबंधित प्रश्न
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Gel
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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.
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| Column I | Column II |
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| (ii) Pumice stone | (b) dispersion of solid in liquid |
| (iii) Milk | (c) dispersion of gas in solid |
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