Standard potential of electrode

Table 3.2 Standard potentials of electrodes of the first kind at 25°C. (From the CRC Handbook of Chemistry and Physicsy recalculated to the standard pressure of 102 kPa)... 

Standard potential of electrode reaction (standard electrode potential), V... 

Although the nickel-containing systems have been extensively studied also by electrochemical methods [1] due to their practical importance, for example, in electrochemical power sources (Ni—Fe, Ni—Cd, Fi—NiF2 batteries), in corrosion-resistant alloys (tableware, coins, industrial instruments) as well as due to their interesting (magnetic, spectral, catalytic) properties most of the standard potentials of electrode... 

The effect of the solvent on the standard potential of electrode reactions can be derived from a thermodynamic cycle. In the case of the ion-transfer type of reaction, where the reduced form is the metal deposited on the solid electrode, we have... 

By international convention, the standard potentials of electrodes are tabulated for reduction half-reactions. These indicate the tendencies of the electrodes to behave as cathodes toward the SHE. Electrodes with positive values for reduction half-reactions act as cathodes versus the SEfE. Those with negative values for reduction half-reactions act as anodes versus the SEfE. 

Table 1.1. Standard potentials of electrode reactions of metals in aqueous medium at 25°C... 

When one wants to calculate the equilibrium constant of reaction (1.2.3) from the standard potentials of the system hexacyanoferrate(II/III) and 2H" /H2, it is essential that one writes this equation with the oxidized form of the system and hydrogen on the left side and the reduced form and protons on the right side. Only then does the sign convention hold true and Eq. (1.2.13) yields the equilibrium constant for the reaction when the tabulated standard potentials are used. Note also that the standard potential of the hydrogen electrode is 0 V for the reaction written as 2H+ - - 2e H2, or written as H+ - - e 1 2- Table 1.2.1 gives a compilation of standard potentials of electrode reactions. (Standard potentials are available from many different sources [2].) Although only single redox couples are listed, the standard potentials of each system always refer to the reaction ... 

In many cases, standard potentials of electrode reactions can be determined by electrochemical measurements. However, this is not trivial for the following reasons according to the Nernst equation, one will measure E = E when the activities of all species are 1, and, of course, at 25°C and 1 bar pressure. However, the activity condition is hard to realize as, at the high concentrations which would be necessary to realize it, the activity coefficients strongly deviate from 1. Therefore, one measures the potentials at concentrations orders of magnitude lower and extrapolates the linear part of the dependence to unit activities. The standard potential can also be calculated from the standard enthalpies and entropies of the involved species. 

Table 1.2.1 Standard potentials of electrode reactions F. Scholz... 

A list of standard potentials of electrode reactions, organized by numerical value (Table 2.8), is referred to as series of standard potentials of eleelrode reactions or electromotive force series. A more complete set of such data can be found in reference [6],... 

With (2.159), it is possible to define an energy scale of the electrons that corresponds to the scale of the standard potentials of electrode reactions. 

Galvanic series are fundamentally different from the series of standard potentials of electrode reactions (Chapter 2), which is based entirely on thermodynamic quantities. In a galvanic series, the value of the potential and the relative positions of the metals in the series can vary depending on the environment. Furthermore, individual metals may appear twice in the same galvanic series, once each for the active and the passive states. For example, according to Table 7.7, stainless steel in the active state is less noble than copper, while for the same steel in the passive slate... 

Table 1.2.1 gives a compilation of standard potentials of electrode reactions. (Standard potentials are available from many different sources [2].) Although only single redox couples are listed, the standard potentials of each system always refer to the reaction ... 

In many cases, standard potentials of electrode reactions can be determined by electrochemical measurements. However, this is not trivial for the following rea-... 

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