Fractional distillation is the method used to separate a mixture of two miscible liquids having different boiling points. The more volatile liquid distills over first and is collected in a receiver. The two fractions are redistilled separately a number of times to ensure complete purity of the liquids. Sublimation is used to separate a non-volatile solid from a volatile one. Iodine, camphor, naphthalene, benzoic acid etc. are purified by this method as they readily sublime i.e., change directly from solid to gas on being heated. Filtration is a method used to separate insoluble impurities from a liquid.
Crystallization is the most common method to purify organic solids. This method is based upon differences in their solubility in a given solvent or mixture of solvents.