Transference number cation constituent

Evidence from Transference Numbers for the Correctness of the Onsager Equation. An important and quite sensitive test of the validity of the Onsager equation, and of the ideas underlying it, is afforded by transference number measurements. It will be recalled from the discussion in Chapter 3, that the Arrhenius theory of ionization assumes that ions have the same mobilities at all concentrations. The transference number, f+, of the cation constituent of a binary electrolyte is... 

Fig. 5.10.1. Dependence on concentration of the cation-constituent transference number of KCl at 25°C in 50 mol % methanol-water ...

The equation necessary for their interpretation is 5.8.7. At concentrations well below the conductance minimum, where the presence of ionic triplets may be disregarded, the cation-constituent transference number (with LiBr as the example) becomes ... 

Cation-Constituent Transference Numbers and Conductance Ratios in Media of Low Dielectric Constant at 25°C... 

The parameter reflects interactions of the cation-constituent with the solvent and with itself. 1 likewise for the anion-constituent, while 1 is a measure of the degree of coupling between the motions of cation- and anion-constituent. The 1 approach has been most actively fostered by Don Miller (TtO 111. 115). An alternative method of representation, introduced by Gerhard Hertz (116.1171, is based on velocity correlation coefficients. There are six of these for a binary electrolyte with self-diffusion coefficients being required to evaluate them. Sets of vcc values have recently been published for concentrated solutions of electrolytes which exhibit strong complexation like Cdl (118). The main problem in calculating these turned out to be a deficiency in suitable transference number information ... 

This simple definition is invalid if the electrolyte is no longer ideal and contains, for example, ion associates. The transference number has to be defined much more generally the transference number of a cation- or anion-constituent R is the net number of faradays carried by that constituent in the direction of the cathode or anode, respectively, across a reference plane fixed with respect to the solvent, when 1 F of electricity passes across the plane [436]. With this definition the transference number tR can also be negative, for example, if an ion A+ is carried in a net transport as an ion-constituent AX2 to the anode. 

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