Free energy cell potential, electrical work

Cell Potential, Electrical Work, and Free Energy... 

Relating the free energy change to electrical work and cell potential (701) ... 

The equals sign is valid for a reversible i —> 0) conversion the greater than sign is valid for an irreversible conversion (finite i). Hence, an electrochemical cell delivers electric work equal to the free energy ehange only at infinitesimal current flow under these eonditions the cell potential is the OCV and the electric work delivered is the maximum ITei max = nPVoc = -AG (n is the number of moles of transferred electrons and Fthe Faraday constant). 

We now consider briefly the matter of electrode potentials. The familiar Nemst equation was at one time treated in terms of the solution pressure of the metal in the electrode, but it is better to consider directly the net chemical change accompanying the flow of 1 faraday (7 ), and to equate the electrical work to the free energy change. Thus, for the cell... 

An electrochemical cell generates a potential difference E. (The symbol E, commonly used in electrochemistry, refers to electromotive force, an archaic term for potential difference.) The electrical work done when n moles of electrons is passed by the cell can be found using Eq. (15-1), w = -nFE. It can be shown that the electrical work done by an electrochemical cell, at constant temperature and pressure, is equal to the change in Gibbs free energy of the cell components,... 

The amount of energy required to move a charge of F coulombs through a potential difference can be related to the free energy available to do useful work. The relation between the standard free-energy change of a reaction and the electrical potential of the corresponding half cell can be expressed as... 

Recall that free energy is related to the maximum possible amount of work that can he done hy the system. In the case of a galvanic cell, the work done is electrical work, so we can state the relationship between fi-ee energy and the cell potential as... 

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