Potentials of reference electrodes

Table 8.20 Potentials of Reference Electrodes in Volts as a Function of...

Table 8.21 Potentials of Reference Electrodes (in Volts) at 25°Cfor Water-...

It is apparent that since the electrode potential of a metal/solution interface can only be evaluated from the e.m.f. of a cell, the reference electrode used for that purpose must be specified precisely, e.g. the criterion for the cathodic protection of steel is —0-85 V (vs. Cu/CuSOg, sat.), but this can be expressed as a potential with respect to the standard hydrogen electrode (S.H.E.), i.e. -0-55 V (vs. S.H.E.) or with respect to any other reference electrode. Potentials of reference electrodes are given in Table 21.7. 

Potentials of reference electrodes in aqueous solutions at 25 C (from Reference Electrodes, eds. D.J.G, Ives and G.J, Janz, Academic Press, New York, 1961)... 

V = voltage of the completed circuit constant = potential of reference electrode R = the gas constant T — the absolute temperature F = the Faraday constant... 

TABLE 8.8 Potentials of Reference Electrodes (in volts) as a Function of Temperature... 

Figure 17.3 Equilibrium potentials of reference electrodes in EMIBF4, PC, and H2O.

Oxidation and Reduction Equilibria and Microbial Mediation Table 8.4. Potentials of Reference Electrodes"... 

TABLE 23 1 Potentials of Reference Electrodes in Aqueous Solutions... 

Table 15.3 Potentials of Reference Electrodes at Various Temperatures...

Choice of reference electrodes is one of the most important points in electrochemical measurements in ILs. The reference electrodes are required to show stable electrode potentials, which are usually determined by an equilibrium between reversible redox couples. The redox reaction between silver and silver cation, Ag/Ag(I), is often used as the redox couple for reference electrode in conventional nonaqueous electrolytes. The reference electrode based on Ag/Ag(l) has been also used in various ILs. However, the potentials of Ag/Ag(l) reference electrodes are different in different ILs since the Gibbs energy for formation of Ag(I) depends on the ions composing the ILs. Therefore, it is necessary to calibrate the potentials of reference electrodes against a conunon standard redox potential. A redox couple of ferrocenium (Fc" ) and ferrocene (Fc) is often used for this purpose although its redox potential is considered slightly dependent on BLs. Platinum or silver electrodes immersed in ILs are sometimes used as quasi-reference electrodes. The potentials of these quasi-reference electrodes may seem to be stable in the ILs without any redox species. However, their potentials are unstable and unreliable since they are not determined by any redox equilibrium. Thus, use of quasireference electrodes should be avoided even when the potentials are calibrated by Fc /Fc couple. 

Table 2.2 Effect of electrolyte concentration on the potential of reference electrodes...

Potentials of reference electrodes in SHE scale at temperatures between 10 and 35°C. According to [8]. 

The potential of reference electrodes should be constant, established quickly and not vary much if a few microamperes are passed through the electrode. In other words, the electrode should have a minimal resistance. This resistance should be independent of the direction of current flow and should... 

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