Fractional crystallisation- Purification of organic compound

The method of separation of diverse components of a mixture by repeated crystallisations is termed as fractional crystallisation. The mixture is dissolved in a solvent where the two components have diverse solubilities. While a heated saturated reaction of this mixture is permitted to cool, the less soluble elements crystallises out first when the more soluble substance stay in solution.

The mother liquor left after crystallisation of the less soluble component is once again concentrated and after that allowed to cool when the crystals of the more soluble component are obtained. So the two elements divided are recrystallized from similar or different solvent to yield both of the components of the mixture in pure form. Fractional crystallisation may be employed to divide a mixture of KclO₃ (less soluble) and KCl (more soluble).