Redox Reactions in Non-Aqueous Solutions

The characteristics of redox reactions in non-aqueous solutions were discussed in Chapter 4. Potentiometry is a powerful tool for studying redox reactions, although polarography and voltammetry are more popular. The indicator electrode is a platinum wire or other inert electrode. We can accurately determine the standard potential of a redox couple by measuring the electrode potential in the solution containing both the reduced and the oxidized forms of known concentrations. Poten-tiometric redox titrations are also useful to elucidate redox reaction mechanisms and to obtain standard redox potentials. In some solvents, the measurable potential range is much wider than in aqueous solutions and various redox reactions that are impossible in aqueous solutions are possible. 

In the potentiometric redox titrations shown in Section 4.4, Cu(II) in AN was often used as a strong oxidizing agent. The following is the procedure employed by Senne and Kratochvil [29] for determining the accurate value of the standard potential of the Cu(II)/Cu(I) couple in AN  

In order to eliminate the effect of E), eI1 is obtained, as shown in Table 6.7, by gradually decreasing Ci, c2 and c3 but keeping c constant then, is determined as the value of E(eU extrapolated to zero values of clt c2 and c3. Here can be expressed by 

If the Debye-Hiickel theory is used for the activity coefficients, Eq. (6.11) can be written as  

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