Which solvent should be added second during the recrystallization process?

In the recrystallization process, the selection of solvents and the order in which they are added can significantly affect the purity and yield of the compound being purified. The primary goal of recrystallization is to dissolve the impure solid in a hot solvent and then allow it to slowly crystallize out as the solution cools.

In this case, the solvent chosen to be added second is ethanol. Ethanol is typically selected due to its solvent properties, particularly its ability to dissolve a wide range of organic compounds at elevated temperatures while being less effective at lower temperatures. The strategy is often to first use a solvent in which the compound of interest is quite soluble at high temperatures before introducing a second solvent that is less polar or that decreases solubility at lower temperatures.

Adding ethanol second allows for greater control over the recrystallization process. If a compound is more soluble in ethanol than in another solvent, adding it second can lead to better formation of crystals upon cooling, as the solubility will decrease more effectively when the solution begins to cool. This technique helps in maximizing the recovery of pure crystals while minimizing the amount of the compound that remains dissolved.

In summary, ethanol serves as the second solvent in this scenario because it optimally complements the recrystallization