Many operations in the industry of chemical processes involving mass transfer from one phase to another. Usually a phase component will be transferred to a greater extent than another, so that there is a separation of the components of the mixture. The chemical engineer is interested in the distribution of the components of the mixture between two phases in equilibrium and the rate of transfer of components from one phase to another. There are a number of basic operations whose purpose is to separate the components of a mixture, in whole or in part. The mixture can be homogeneous or not. The separation is achieved by transfer between two phases in contact must be immiscible or at least if they are partially miscible, must submit an interval (small or large) of immiscibility. The mass transfer rate should be taken into consideration in the design of the machine where the two phases will be in continuous contact and where it will be a continuous exchange of mass between the phases. Initial calculations used in equipment design or evaluation of the behavior of existing equipment, are based on simple stoichiometric relationships and balance.