Crystallization can be defined as the process through which the atoms/molecules of a substance arrange themselves in a well-defined three-dimensional lattice and consequently, minimize the overall energy of the system. Crystallization is a technique used for the purification of substances. A separation technique to separate solids from a solution.
Purification by crystallization
The crystallisation method can be used for the purification of those mixtures which
i. Contains insoluble and/or soluble impurities.
ii. Have crystalline nature.
iii. Cannot be separated by filtration as some impurities are soluble.
By the technique of crystallization, pure solids are separated from impurities. For example, salt obtained from the sea is separated from impurities; crystals of alum (Phitkari) are separated from impure samples.