Final answer:
The answer is option B. When recrystallizing an organic compound to increase its purity, the recrystallization mixture of solute and solvent should be cooled slowly. Slow cooling allows for the formation of well-organized crystals of the desired compound, while impurities remain in solution or form smaller crystals.
Step-by-step explanation:
When recrystallizing an organic compound to increase its purity, the recrystallization mixture of solute and solvent should be cooled slowly.
By cooling the mixture slowly, it allows the solute to form well-organized crystals, while impurities remain in solution or form smaller, less well-formed crystals. Slow cooling also allows for the separation of impurities from the desired compound, resulting in a higher purity.
For example, let's say we want to recrystallize a compound X. We dissolve compound X in a suitable solvent at an elevated temperature, and then we slowly cool the mixture to room temperature or below. As the mixture cools, compound X will start to crystallize, while impurities are left behind in the solution or in smaller crystals. By filtering or decanting, we can separate the crystals of compound X from any remaining impurities, resulting in a purer product.