Purification of Copper Sulphate by Crystallization Video Lecture - Class 11

Ans. The purpose of purifying copper sulfate by crystallization is to remove impurities and obtain a pure form of copper sulfate. Crystallization is a process that involves dissolving the impure copper sulfate in water and then allowing it to cool down slowly, causing the formation of pure copper sulfate crystals.

Ans. Crystallization helps in purifying copper sulfate by utilizing the differences in solubility between the impurities and copper sulfate. When the impure copper sulfate is dissolved in water, the impurities remain in the solution while the copper sulfate molecules form crystals as the solution cools down. These crystals can be separated from the solution, resulting in a purified form of copper sulfate.

Ans. The steps involved in the crystallization process of purifying copper sulfate are as follows: 1. Dissolve the impure copper sulfate in water to form a saturated solution. 2. Heat the solution to increase the solubility of copper sulfate. 3. Filter the solution to remove insoluble impurities. 4. Allow the solution to cool down slowly to room temperature, promoting the formation of copper sulfate crystals. 5. Separate the crystals from the remaining solution using filtration or decantation. 6. Wash the crystals with cold water to remove any remaining impurities. 7. Dry the purified copper sulfate crystals to obtain the final product.

Ans. Several factors can affect the success of the crystallization process in purifying copper sulfate. These include: - Temperature: Cooling the solution slowly and at a controlled rate allows for the formation of larger and purer crystals. - Impurity concentration: Higher concentrations of impurities can interfere with the formation of pure copper sulfate crystals. - Stirring: Agitating the solution during cooling can prevent the formation of large crystals and lead to impurities being trapped within the crystals. - Solvent choice: Using the appropriate solvent and concentration can enhance the solubility difference between copper sulfate and impurities, aiding in the purification process. - Cooling rate: A slow cooling rate promotes the formation of larger crystals and reduces the presence of impurities within the crystals.

Ans. Common impurities found in copper sulfate include iron, zinc, and other metal ions. These impurities can be removed during the crystallization process by several methods: - Filtration: Insoluble impurities can be removed by passing the solution through a filter, which traps the impurities and allows the pure copper sulfate solution to pass through. - Decantation: If the impurities settle at the bottom of the solution, decantation can be used to carefully pour off the pure copper sulfate solution while leaving the impurities behind. - Washing: Washing the crystals with cold water helps remove any soluble impurities that may be adsorbed on the crystal surface. - Selective crystallization: By controlling the temperature and concentration, it is possible to selectively crystallize copper sulfate while leaving impurities in the solution or as amorphous solids, thus further purifying the final product.