Conducting species

Electrical Resistance—Conductivity. Most fillers are composed of nonconducting substances that should, therefore, provide electrical resistance properties comparable to the plastics in which they are used. However, some fillers contain adsorbed water or other conductive species that can gready reduce their electrical resistance. Standard tests for electrical resistance of filled plastics include dielectric strength, dielectric constant, arc resistance, and d-c resistance. 

Proposed reaction mechanisms have suggested that in many rate processes the nature of the conducting species may change during the course of decomposition. There is evidence [364] that, even in the absence of pyrolysis, the conducting entity may vary with the physical form of the reactant. 

The Chemkin package deals with problems that can be stated in terms of equation of state, thermodynamic properties, and chemical kinetics, but it does not consider the effects of fluid transport. Once fluid transport is introduced it is usually necessary to model diffusive fluxes of mass, momentum, and energy, which requires knowledge of transport coefficients such as viscosity, thermal conductivity, species diffusion coefficients, and thermal diffusion coefficients. Therefore, in a software package analogous to Chemkin, we provide the capabilities for evaluating these coefficients. ... 

As for ehloride systems, (K, Cai/2)C1 and (X, Dy 3)CT have been studied. The isotherms for the latter are shown in Fig. 16, w here k decreases with increasing concentration of Dy, which is due to the tran-quilization effect of Dy Y However, does not change as much while Xjy is high, but at high x, decreases, which may be due to an increase in the species [DyCl ] ". However, it has not been ascertained that this species actually becomes the electrolytic conducting species since this depends on the lifetime of this species. 

It is not as easy as it appears to know whieh are the eleetrieally conducting species in molten salts. It seems to be nearly impossible to determine the electrically conducting species by experiment alone. ... 

Based on quite similar equilibria for the nitrate system (Li, K)N03, Lantelme and Chemla quantitatively estimated the existing species so that the experimental mobilities and self-diffusion coefficients could be obtained consistently. This could be successfully done. However, no direct evidence has been obtained yet that such species as [LiBrn] "and are really electrically conducting species. 

This model is similar to the associated species model in that a chemical equilibrium is assumed between existing species, and it is different in that in the latter only a nonassociated ionic species is assumed to be the electrically conducting species. 

The dynamic dissociation model resembles the association (or dissociation) model in that electrically conducting species are assumed to he nonassociated species, and it differs from the association model in that in the dynamic dissociation model the dissociation process itself is the electrically conducting process, while in the association model, the amount of the dissociated species is constant according to the chemical equilibrium. 

It is known that the conducting species in solutions of aluminium halides in alkyl halides are complex for instance solutions of aluminium bromide in ethyl bromide [70] contain the ions Al2Br5+ and Al2Br7 ... 

Hydroxyl ions are the conducting species in the electrolyte and the net cell reaction is ... 

The second column is called a suppressor column. Its function is to convert the eluent to a less conductive species while converting sample ions to a common form. This system enables conductimetric detection of the sample ions in a low conductivity background. The ion-exchange suppressor reactions are also shown in Figure 1. In the case of anion analysis, sodium carbonate and/or bicarbonate eluent is converted to a weakly conductive dilute carbonic acid while the sample ions are converted to strong-... 

The electron transfer mechanism for the CNT-MPc modified electrode may be represented as shown in Figure 3, where the immobilized MPc and CNT act as electrocatalyst and electron conducting species, respectively. 

Hitherto we have dealt with model FICs that are mostly useful as solid electrolytes. The other class of compounds of importance as electrode materials in solid state batteries is mixed electronic-ionic conductors (with high ionic conductivity). The conduction arises from reversible electrochemical insertion of the conducting species. In order for such a material to be useful in high-energy batteries, the extent of insertion must be large and the material must sustain repeated insertion-extraction cycles. A number of transition-metal oxide and sulphide systems have been investigated as solid electrodes (Murphy Christian, 1979). 

If the system behaved ideally, the specific conductances should be additive. Figure 7 shows the specific conductance of the solution corrected (by subtraction) for the specific conductances of the acetone and lithium bromide for various fixed amounts of lithium bromide as a function of bromosuccinic acid concentration. Inasmuch as this should be equal to the equivalent conductance of bromosuccinic acid, if there were no interaction among the conducting species all four curves should coincide with the curve for no lithium bromide. Clearly, some type of interaction must occur. 

The two mass action equilibria previously indicated have been used in conjunction with a modified form of the Shedlovsky conductance function to analyze the data in each of the cases listed in Table I. Where the data were precise enough, both K2 and K were calculated. As mentioned previously, the K s so evaluated are practically the same as those obtained for ion pairing in solutions of electrolytes in ammonia and amines. This is encouraging since it implies a fairly normal behavior (in the electrolyte sense) for dilute solutions of metals. Further support of the proposed mass action equilibria can be found in the conductance measurements of sodium in NH8 solutions with added salt. Bems, Lepoutre, Bockelman, and Patterson (4) assumed an additional equilibrium between sodium and chloride ions, associated to form NaCl, to compute the concentration of ionic species, monomers, and dimers when the common ion electrolyte is added. Calculated concentrations of conducting species are employed in the Onsager-Kim extension of the conductance theory for low-field conductance of a mixture of ions. Values of [Na]totai ranging from 5 X 10 4 to 6 X 10 2 and of the ratio of NaCl to [Na]totai ranging from zero to 28.5 are included in the calculations. 

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