Potential outer electric

The inner electrical potential 0 may consist of two components. Firstly, the phase may possess some excess electrical charge supplied from outside. This charge produces an outer electrical potential 0. This is defined as the limit of the ratio w/q for <7—>0, where w is the work expended for the infinitely slow transfer of charge q from an infinite distance to a point in the vacuum adjacent to the surface of the given phase and just outside the range of image forces. A particle transferred from this point further on in the... 

The component x is defined as the limit of the ratio w /q for q—>0, where w is the work expended in the transfer of charge q, from a point at which the outer electrical potential 0 is defined, into the bulk of the phase. 

The outer electrical potential of a phase is the electrostatic potential given by the excess charge of the phase. Thus, if a unit electric charge is brought infinitely slowly from infinity to the surface of the conductor to a distance that is negligible compared with the dimensions of the conductor considered (for a conductor with dimensions of the order of centimetres, this distance equals about 10 4cm), work is done that, by definition, equals the outer electric potential ip. 

Thus the compensating voltage U yields the difference between the outer electrical potentials of the metal and the solution with which it is in contact. 

Apparently no cell reaction can occur in this cell as the vacuum prevents movement of species between phases 1 and 3. The measured difference in the inner electric potentials of phases 5 and 1 is equal to the difference in outer electric potentials between phases 5 and 3,... 

The effects of the crystallographic face and the difference between metals are evidence of the incorrectness of the classical representations of the interface with all the potential decay within the solution (Fig. 3.13a). In fact a discontinuity is physically improbable and experimental evidence mentioned above confirms that it is incorrect, the schematic representation of Fig. 3.136 being more correct. This corresponds to the chemical models (Section 3.3) and reflects the fact that the electrons from the solid penetrate a tiny distance into the solution (due to wave properties of the electron). In this treatment the Galvani (or inner electric) potential, (p, (associated with EF) and the Volta (or outer electric) potential, ip, that is the potential outside the electrode s electronic distribution (approximately at the IHP, 10 5cm from the surface) are distinguished from each other. The difference between these potentials is the surface potential x (see Fig. 3.14 and Section 4.6). 

Fig. 1.2.2 (a) Schematic situation at the border of a phase with vacuum. is the outer electric potential of phase a, i.e., the work that must be done when a unit charge is transferred from infinity (in the vacuum) to the surface of phase a. (The difference in the two outer electric potentials of two different phases is called the Volta potential difference.) x is the surface electric potential of phase a, i.e., the work to be done when a unit charge is transferred from the surface into phase a, and is the inner electric potential of phase a, i.e., the work to be done when a unit charge is transferred from infinity (in vacuum) into the inner of phase a. is a nonmeasurable quantity, whereas 1 can be calculated and measured. The three potentials are interrelated as follows (j> = + x -... 

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