The transfer of mass from a higher concentration region to a lower concentration region in a mixture is known as mass transfer. The mass transfer is similar to heat transfer in many aspects. In heat transfer, heat is transferred toward the lower temperature decreasing the temperature of the source and, in mass transfer, the mass is transferred toward the lower concentration matter decreasing the concentration of the source. Both depend on the driving potential and the resistance that exist between the two sources. Mass transfer takes place from liquid to gas and solid, from solid to gas, and also from gas to gas. It depends on the molecular spacing of the receiving mass and larger spacing gives a higher diffusion ...