Consider an equimolar binary mixture (composed of species and ) fed to a gas permeation module. The feed rate is equal to . This Demonstration computes the permeate composition , the stage cut, , and the required membrane area, (expressed in ), for user-specified values of the desired reject composition, the ideal separation factor (i.e., the ratio of the permeabilities of the two species present in the feed mixture), pressure in cmHg on both the feed and the permeate sides of the membrane. For the computation of the area, two additional pieces of information are required: (1) the membrane thickness, , chosen equal to and (2) the permeability of species ,