Question

How is crystallization better than evaporation?

Answer 1

i. The process of evaporation give residues which may contain impurities. When there is a requirement to obtain solid without impurity, crystallization method is preferred.

ii. In general practice, impure solids are obtained by evaporation and are further purified by crystallization. e.g. salt obtained from sea water is further purified by this method.

iii. In some cases e.g. sugar crystal cannot be obtained by simple evaporation technique because sugar gets charred on heating to dryness. In such cases, crystallization technique is applied.