Equivalent weight electron-transfer

Some substances have more than one electron-transfer equivalent weight. For example, consider iron in the following reactions ... 

The electron-transfer equivalent weight is defined in Chapter 19 as the weight of material oxidized or reduced by one mole of electrons. This quantity is easily calculated by dividing the coefficient of each component of the halfreaction that is involved in the reaction in question by the number of moles of electrons ( )in the half-reaction. For example,... 

From the electronic view, equivalent weight turned out to represent the relative weights of elements involved in a single electron shift of this sort. The equivalent weight is, after all, the atomic weight divided by the valence (see page 111) or, in other words, the atomic weight divided by the number of electrons transferred. 

Does a soil-fluid-chemical system behave as an active electrochemical system or a passive electrical conductor under the influence of a DC electric field This is a fundamental question of significant implications. The evaluation criterion that can be used to differentiate the two systems of completely different nature is vested in Faraday s laws of electrolysis, as the transfer of electrons from the electrodes to the system and vice versa in an ideal electrochemical system is invariably associated with chemical reactions obeying Faraday s laws of electrolysis (Antropov, 1972). The two important fundamental laws of electrolysis can be simply expressed as follows (a) the amount of chemical deposition is proportional to the quantity of electric charges flowing through the system in an electrolytic process, and (b) the masses of different species deposited at or dissolved from electrodes by the same quantity of electric charges are directly proportional to their equivalent weights (Crow, 1979). 

A cosurfactant-induced electron-transfer phenomenon is illustrated by the square wave voltammetry (SWV) data in Figs. 1 and 2 for the oxidation of Fe(CN)6 and for the reduction of RuCNHs) in a series of reverse water-AOT (sodium bis(2-ethylhexyl) sulfosuccinate)-toluene microemulsions. These data were obtained for a series of microemulsions containing varying amounts, of the cosurfactant acrylamide [29,30]. Formulations are described in the caption to Fig. 1. The amount of water, AOT, and toluene is kept essentially constant in each series of microemulsions, and the amount of cosurfactant is varied. In such formulations, the mole fraction of cosurfactant (or equivalently weight %) is an effective field variable. In Fig. 2 it can be seen that the onset of facilitated Fe(CN)6 oxidation occurs at a 1.7% and the onset of Ru(NH3)6 reduction occurs at w 2.3%. Identical behavior to that illustrated in Fig. 2 was obtained for limiting currents in slow-scan cychc voltammetry. It could then be concluded that this threshold phenomenon occurs under diffusion-limiting conditions and is not a simple manifes-... 

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