Question

Water is a good choice of solvent because it is benign, cheap and readily available. Identify two characteristics that make water a good choice for the recrystallization solvent for benzoic acid? (What are the characteristics of a good recrystallization solvent?)

Answer 1

Explanation:

Characteristics of good solvent choice for the recrystallization.

1. Water has low solubility of benzoic acid at room temperature.

2. Cold water's low solubility of  benzoic acid allows for the high concentration production of crystal. And these crystals could be easily soluble in hot water.

3. Water dissolves soluble impurities well at  the room temperature.

Answer 2

Explanation:

It is known that a compound is soluble when the boiling point of the solvent is high. Whereas at normal temperature of the solvent it will have low solubility.

And, if the solute is highly soluble into the solvent at normal temperature then it is difficult to recrystallize the solute.

Hence, in order to recrystallize the solute particles it is necessary that impurities will be highly soluble at the room temperature or they should remain insoluble into the hot solvent.

As a result, there will not take place any reaction between the solute and solvent.

Since, benzoic acid is non-polar in nature and water is a polar solvent so, it will not easily dissolve in water. Therefore, it will readily evaporate in order to give the pure compound.