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Methods of Preparation of Colloids Video Lecture | Chemistry Class 12 - NEET

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FAQs on Methods of Preparation of Colloids Video Lecture - Chemistry Class 12 - NEET

1. What are the different methods of preparation of colloids?
Ans. There are several methods of preparing colloids, including: - Dispersion method: This involves breaking down larger particles into colloidal particles by methods such as grinding, milling, or ultrasonication. - Condensation method: In this method, small colloidal particles are formed by the condensation of larger molecules or ions. - Chemical method: Colloids can be prepared by chemical reactions, where reactants are selected to yield colloidal particles. - Electrolytic method: Colloids can be formed by the electrolysis of certain electrolytes. - Mechanical method: This method involves the shearing of larger particles to form colloidal particles.
2. How does the dispersion method work for the preparation of colloids?
Ans. The dispersion method involves reducing the size of larger particles to colloidal size. This can be achieved by various techniques such as grinding, milling, or ultrasonication. In grinding, a solid material is ground down using a mortar and pestle or a ball mill to create smaller particles. Milling involves using a milling machine or a colloid mill to break down larger particles. Ultrasonication uses high-frequency sound waves to break down particles into smaller sizes. These methods help in achieving a colloidal dispersion by reducing the particle size to the required range.
3. Can you provide an example of the condensation method for preparing colloids?
Ans. One example of the condensation method for preparing colloids is the formation of colloidal gold. In this method, gold chloride is reduced by adding a reducing agent, such as sodium citrate or sodium borohydride, to form small gold nanoparticles. These nanoparticles then condense further to form larger colloidal particles. The size of the particles can be controlled by adjusting the concentration of the reducing agent and reaction conditions. This method is widely used in industries for the preparation of gold colloids used in various applications such as catalysis, electronics, and medicine.
4. How does the chemical method work for the preparation of colloids?
Ans. The chemical method involves the formation of colloidal particles through a chemical reaction. This method relies on the selection of reactants that can yield colloidal particles. For example, the reaction between a metal salt and a reducing agent can result in the formation of metal nanoparticles. Similarly, the reaction between an acid and a base can produce colloidal particles called sols. The chemical method allows for precise control over the size, shape, and composition of the colloidal particles by adjusting the reaction conditions and reactant concentrations.
5. What is the electrolytic method for the preparation of colloids?
Ans. The electrolytic method involves the electrolysis of certain electrolytes to form colloidal particles. Electrolytes are substances that dissociate into ions when dissolved in water. By passing an electric current through the electrolyte solution, ions can migrate towards the electrodes and undergo specific reactions to form colloidal particles. For example, the electrolysis of silver nitrate solution can produce colloidal silver particles. The electrolytic method offers a way to prepare colloids with precise control over their size and stability.
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