Real reverse of charge concentration

Thus the hexol nitrate concentration needed for an arabinate sol of given concentration consists always of two parts viz, the real reversal of charge concentration and a fictitious concentration — the quantity fixed by and proportional to the arabinate present. 

At moderate arabinate concentrations (right side of the figure) the hexol nitrate concentration is thus for the greatest part fictitious, only at very small arabinate concentrations, (to the extreme left in Fig. 2) it would be practically equal to the real reversal of charge concentration. 

The figure shows the general effect in choosing a lower valent cation, which consists in a nearly parallel displacement of the straight line towards higher con-centrations. " The nearly equal slope of both lines means that the reciprocal La number will indeed be practically the same as the reciprocal hexol number. The main effect consists thus in an enormous increase of the real reversal of charge concentration, the latter being 7 X 10 N for hexol nitrate and 3.6.10 for La(NOg)3. 

Summarising we may say that hexol nitrate is at the moment the salt best suited for the experimental method discussed in this subsection, the hexol cation by its high valency giving very low real reversal of charge concentrations and by its nature of a strong complex ion being hardly hydrolysed at low concentration (see also p. 300, note 1). 

Unpublished investigations show even, that among basic dyes examples may be found, which because of their very low real reversal of charge concentrations, might possibly be used in a similar way as discussed for hexoi nitrate in 1 b (p. 262), for obtaining similar reciprocal dye numbers . Such dyes should however be available in a well defined and absolutely pure state. 

The following explanation of the occurrence of this curious transition sequence starts from the idea, that we have here no real exception to the rule frequently found that lengthening of the carbon chain lowers the reversal of charge concentration. It is thought that this influence is present in the whole series of dicarboxylic acids, in the first terms of the series it is only pvercompensated by another influence acting in the opposite direction. 

A real electrode with some degree of reversibility will therefore allow a steady state current to pass in the sense that such a current obeys Faraday s laws, it is termed a faradic current. A completely polarizable electrode passes no faradic current. In transient or ac experiment however, a polarizable electrode and a reversible electrode both pass a nonfaradic current, corresponding to charging or discharging of the interface capacitance and perhaps changes in the nature and concentration of any adsorbed species. The distinction between the two types of current is important in developing expressions for the impedance of the electrode-electrolyte interface. 

Ru(NH3)6] " in aqueous electrolytes of sufficiently high concentrations represents a real-life example of an extremely fast charge transfer process that is not necessarily burdened by the influence of R, . Therefore, the voltammetry of the [Ru(NH3)6] process should ideally fit the theoretical predictions for an electrochemically reversible process. 

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