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Electrode potentials of successive elementary half-reactions cannot be directly added. However, the corresponding Gibbs free energy changes (∆G°) must satisfy ∆G° = – z FE°, where z electrons are transferred, and the Faraday constant F is the conversion factor describing Coulombs transferred per mole electrons. Those Gibbs free energy ...
The easiest way to proceed is simply to use energies (nE) directly expressed in electron-volt (eV), because the Faraday constant F and the sign minus simplifies on both side of the equation. So, the values of E in volt must be simply multiplied by the number (n) of electron transferred in the considered half-reaction.
The values below are standard apparent reduction potentials (E°') for electro-biochemical half-reactions measured at 25 °C, 1 atmosphere and a pH of 7 in aqueous solution. [ 1 ] [ 2 ] The actual physiological potential depends on the ratio of the reduced ( Red ) and oxidized ( Ox ) forms according to the Nernst equation and the thermal voltage .
Depiction of common redox reactions in the environment. Adapted from figures by Zhang [1] and Gorny. [2] Redox pairs are listed with the oxidizer (electron acceptor) in red and the reducer (electron donator) in black. Relative favorability of redox reactions in marine sediments based on energy.
In aqueous solutions, redox potential is a measure of the tendency of the solution to either gain or lose electrons in a reaction. A solution with a higher (more positive) reduction potential than some other molecule will have a tendency to gain electrons from this molecule (i.e. to be reduced by oxidizing this other molecule) and a solution with a lower (more negative) reduction potential ...
The decomposition of a reaction into half reactions is key to understanding a variety of chemical processes. For example, in the above reaction, it can be shown that this is a redox reaction in which Fe is oxidised, and Cl is reduced. Note the transfer of electrons from Fe to Cl.
The following list includes the metallic elements of the first six periods. It is mostly based on tables provided by NIST. [9] [10] However, not all sources give the same values: there are some differences between the precise values given by NIST and the CRC Handbook of Chemistry and Physics. In the first six periods this does not make a ...
Standard electrode potentials are available in a table of values. Using these values, the actual electrode potential for a redox couple can be calculated as a function of the ratio of concentrations. The equilibrium potential for a general redox half-reaction (See #Equilibrium constant above for an explanation of the symbols)