What chemical technique is used to separate and purify a solid compound?

What chemical technique is used to separate and purify a solid compound?

• A. Filtration
• B. Recrystallization
• C. Distillation
• D. Sublimation

Answer: (B)

Recrystallization is a widely used technique for separating and purifying solid compounds based on their solubility characteristics. The process involves dissolving the impure solid in a suitable solvent at elevated temperatures, where the solute is more soluble. As the solution cools, the solubility of the compound decreases, leading to the formation of pure crystals while impurities remain dissolved in the solvent. This method effectively exploits differences in solubility to enhance purity. By carefully controlling the cooling rate and sometimes even using additional techniques like scratching the vessel to induce crystallization, high-purity crystals can be isolated. The purified solid can then be collected through filtration, allowing for separation from the residual solvent containing the impurities. Other techniques listed, like filtration, distillation, and sublimation, serve different purposes. Filtration is primarily a mechanical separation method, distillation involves the separation of liquids based on boiling points, and sublimation involves the transition of a solid directly to a gas. Recrystallization specifically targets the purification of solids, making it the most appropriate choice in this context.

Recrystallization is a widely used technique for separating and purifying solid compounds based on their solubility characteristics. The process involves dissolving the impure solid in a suitable solvent at elevated temperatures, where the solute is more soluble. As the solution cools, the solubility of the compound decreases, leading to the formation of pure crystals while impurities remain dissolved in the solvent.

This method effectively exploits differences in solubility to enhance purity. By carefully controlling the cooling rate and sometimes even using additional techniques like scratching the vessel to induce crystallization, high-purity crystals can be isolated. The purified solid can then be collected through filtration, allowing for separation from the residual solvent containing the impurities.

Other techniques listed, like filtration, distillation, and sublimation, serve different purposes. Filtration is primarily a mechanical separation method, distillation involves the separation of liquids based on boiling points, and sublimation involves the transition of a solid directly to a gas. Recrystallization specifically targets the purification of solids, making it the most appropriate choice in this context.