title: Central role of the observable electric potential in transport equations.
abstract: Nonequilibrium systems are usually studied in the framework of transport equations that involve the true electric potential (TEP), a nonobservable variable. Nevertheless another electric potential, the observable electric potential (OEP), may be defined to construct a useful set of transport equations. In this paper several basic characteristics of the OEP are deduced and emphasized: (i) the OEP distribution depends on thermodynamic state of the solution, (ii) the observable equations have a reference value for all other transport equations, (iii) the bridge that connects the OEP with a certain TEP is usually defined by the ion activity coefficient, (iv) the electric charge density is a nonobservable variable, and (v) the OEP formulation constitutes a natural model for studying the fluxes in membrane systems.
authors.affiliation: Departamento de Termodinámica, Universitat de València, E-46100 Burjassot, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Garrido
authors.forename: V
authors.initials: V
authors.lastname: Compañ
authors.forename: M L
authors.initials: ML
authors.lastname: López