Electrode potential European convention

In the past the electrostatic convention has often been called the European convention and the thermodynamic convention popularized by Luitmer (The Oxidation Potentials of the Elements and Their Values in Aqueous Solution Prenlicc-HBlI Englewood Cliffs. NJ, (952) the American convention. In an effort to reduce confusion, the IUPAC adopted the "Stockholm convention" in which electrode potentials refer to the electrostatic potential and end s refer to the thermodynamic quantity. Furthermore, the recommendation is that standard reduction potentials be listed as electrode potentials" to avoid the possibility of confusion over signs. 

The European convention assigns the sign (positive or negative) which the electrode would assume when immersed in a solution of its own ions. Thus a zinc electrode in a solution of Zn2+(aq) would assume a negative potential and E° is —0.763 V. 

The American convention would assign a positive value to E° for the Zn Zn2+(aq) half cell written as an oxidation, but a negative sign if written as a reduction. It is seen that the European convention refers to the invariant electrostatic potential of the electrode with respect to the SHE, whereas the American convention relates to the thermodynamic Gibbs free energy which is sensitive to the direction of the cell reaction. 

IUPAC recommends that electrode potential be reserved for the European convention, whereas the EMF of a half cell is dealt with via the American convention. 

It is not appropriate in this chapter to tabulate quantities of electrochemical data since that required may be obtained from texts on electrodeposition.1 2 However, a brief mention of sign conventions must be made since, particularly in the early literature, confusion can arise. Two conventions have been used the European and the American .3 It is sometimes erroneously stated that the conventions differ only in sign however, the real difference lies in the distinction between the potential of an actual electrode and the EMF of a half cell reaction. 

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