Galvani voltage

Galvani voltage 17i n then forms between the solution (phase I) and the inert metal (phase II), exactly as it would form between two metals (Fig. 22.3). We can calculate the Galvani potential difference or the Galvani voltage, respectively, according to Eq. (22.8) or Eq. (22.9), by inserting the value of the electron potential in the metal, here the commonly used platinum (Pt), and of the redox pair Rd/Ox in the solution (S),... 

Section 3A.2.2 outlines other examples of thermodynamic equilibrium equations for this system. Moreover, keep in mind that the Galvani voltage between the two sides of an interface cannot be obtained in an experiment. The activity of a single ion appears in the equation, and is also a non-measurable quantity (see appendix A.3.2). 

For simple electrochemical cells, the electromotive force, emf, can be easily linked to the thermodynamic reaction quantities by using the same equations as those previously demonstrated for Galvani voltages at an interface in equilibrium. 

According to the exact position of the equilibrium galvani potential for Ca2+-ions on the voltage axis, stimulation or inhibition of the Na+—K+ exchange can be understood. The effect of anions (e.g., MgATP2-) may be similiar as shown in Fig. 4. 

Thus, the Volta potential may be operationally defined as the compensating voltage of the cell of Scheme 16. However, it should be stressed that the compensating voltage of a voltaic cell is not always the direct measure of the Volta potential. The appropriate mutual arrangement of phases, as well as application of reversible electrodes or salt bridges in the systems, allows measurement of not only the Volta potential but also the surface and the Galvani potentials. These possibilities are schematically illustrated by [15]... 

The Galvani potential, 0, of a phase defines the amount of electrical energy, e, required to transport a charge e from an infinitely distant point in a vacuum to a hypothetical point in the interior of the phase where the charge would experience no chemical forces exerted on it. Thus the Daniell cell voltage can be written as ... 

After earlier experiments with static electricity and with Franklin128 fishing for thunderbolts, electrochemistry was born with Galvani s129 electrostatic stimulation of deceased frog muscles in 1791 and Volta s130 development of the "voltaic pile." The methodical and routine study of current versus voltage... 

An especially simple example of Galvani potential differences is the so-called contact potential dijference (or contact voltage) between two metals. The electrons e in a metal can be assigned a chemical potential, similar to ions in a solution. In this case it is the electron potential (We will only attach an index indicating charge such as etc., to formulas and names of substances when it is necessary or useful for clarity. Expressions like e and e will be treated as equal.) will be different depending upon the metal in question. 

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