Thermodynamics of electrochemical systems

Determining the cell potential requites knowledge of the thermodynamic and transport properties of the system. The analysis of the thermodynamics of electrochemical systems is analogous to that of neutral systems. Eor ionic species, however, the electrochemical potential replaces the chemical potential (1). 

This equation links the EMF of a galvanic cell to the Gibbs energy change of the overall current-producing reaction. It is one of the most important equations in the thermodynamics of electrochemical systems. It follows directly from the first law of thermodynamics, since nF% is the maximum value of useful (electrical) work of the system in which the reaction considered takes place. According to the basic laws of thermodynamics, this work is equal to -AG . 

Equation (55) also suggests the introduction of the name surface-chemical potential for [i thus underlining the facts that fi enters into the fundamental equation for a surface phase in the same manner as enters into the corresponding equation for a bulk phase and that generally /t. In these respects is analogous to the electrochemical potential. However, the counterpart of Eq. (55) in the thermodynamics of electrochemical systems is the well-known relation... 

It is well recognized that the addition of a large excess of an inert electrolyte has an effect on the kinetics and thermodynamics of electrochemical systems and in some cases it would be highly desirable to determine the influence of the electrolyte nature and concentration, and of the solvent, on the behaviour of such systems. The unique properties of microelectrodes allow electrochemical studies to be carried out in non-conventional media, such as very resistive solvents or in the absence of electrolyte (4). 

Chapter 2 is devoted to concepts and principles of thermodynamics of electrochemical systems. An overview of thermodynamics of phases in solution and the concept of charged particles are succinctly described as they relate toe electrical potential (voltage) difference between the solution and a metal surface. 

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