Ion Transport Across Membranes: I. Definitions of Membrane Electromotive Forces and of Flows of Electrolytic Solutes

An analysis is given for the treatment of membrane transport phenomena in accord with the theory of steady state thermodynamics. A linear macroscopic theory for discontinuous systems is applied as a postulate. It is shown that as a consequence of the transformation properties of the Onsager reciprocal relations the definition of a membrane electromotive force gives corollary definitions of the flows of electrolytic solutes as a whole in the form of linear combinations of the flows of ionic constituents. It is shown that established conventions which set the activity coefficients of ionic constituents equal to unity at the reference state of infinite dilution lead to a particular definition of the membrane electromotive force which may be applied at any concentration.