A unit operation is related fields of chemical engineering It is the basic step in a process. Unit operations involve a chemical transformation or physical change such as filtration, polymerization, isomerization, separation, crystallization, evaporation and other reactions. In the field of Chemical Engineering separation process is the mass transfer that converts the substance mixture into specific product mixtures. In some cases, a separation may fully divide the mixture into its pure constituents. Separation Techniques are conducted based on the differences between chemical properties, or physical properties like size, shape, mass, density and chemical affinity, between the constituents of a mixture, and are often differentiated according to the specific differences they use to achieve.