Reduced ion concentration

Molar density or concentration Reduced ion concentration, Eq. (3.4.11) Wave speed... 

Reduced ion concentration at anode Reduced ion concentration at cathode Solute gelling concentration Mixing-cup concentration, Eq. (4.4.29), Problem 4.3... 

With and v the number of positive and negative ions produced by the dissociation of one molecule of electrolyte, we can introduce the reduced ion concentration c defined by... 

It was shown in Section 3.4 that if the bulk of a dilute binary electrolyte solution may be assumed electrically neutral, then the distribution of reduced ion concentration is governed by the same convective diffusion equation as for a neutral species with an effective diffusion coefficient related to the difference in charge and diffusion coefficients of the positive and negative ions. Once the concentration distribution has been found, the potential distribution in the solution can be obtained by integrating the equation for current continuity (Eq. 3.4.16) to give... 

As in Section 3.4, it is convenient to express the basic equations in terms of the reduced ion concentration... 

The concentration distribution is fixed by specifying the reduced ion concentration at the anode ... 

Section 5.5 dwelled on the transport of charged mixtures and the derivation of the basic transport equations. Recall that for an infinite diluted mixture, the transport of ions takes place due to their migration in the electric field, diffusion and convection. As in the Section 5.5, we limit ourselves to the study of a binary electrolyte mixture, for which (in the case of electrically neutral mixture) the distribution of reduced ion concentration is described by a convective diffusion equation, with the effective diffusion coefficient given by (5.96). The solution of Eq. (5.94) allows us to find the distribution of electric potential. In Eq. (5.98), we can form scalar products of both parts with dx, where x is the radius-vector, and then use the relation between diffusion coefficients of ions and their mobility D = ATi> . Integrating the resultant expression, we then find the potential difference Ap between two points of the mixture ... 

IfQ > fCjp, precipitation occurs, reducing ion concentrations until Q = K p. 

An integration of the equations discussed above can accurately predict the shape of the AP. These equations can not only predict the shape of the AP but can be used to investigate changes in cellular physiology (such as elevated or reduced ion concentrations associated with disease states), the presence of unusual electrical activity (such as is found with various arrhythmias resulting from myocardial ischaemia or infarction) or how drugs may interact with multiple ion channels concurrently and modulate or alter the AP. 

Thus, the current flowing in the cell due to electromigration and diffusion is thus due to only cation transport. It is the magnitude of this current which we wish to determine for a given value of applied voltage. From the definition of a reduced ion concentration,... 

Because of undesired ionic side products in the form of chlorides, sulfates, and anunonia which may disturb the transfer process, at least part of the aqueous carrier fluid has to be exchanged for purified water to reduce ion concentration in the suspension. Another reason for the reduction of ion concentration is that, at high concentrations, hardly any electrical repulsion between the particles can be achieved [16], The process of exchanging the water can be carried out by, for example, decantation or filtration of the suspension. Both methods have as their aim the retention of particles while the carrier fluid is changed. For decantation, the magnetic particles can be fixed at the bottom of the vessel by a permanent magnet. With the filtration process, selective membranes are needed which separate a particle-free fluid permeated by ionic components from a retentate in which the magnetic particles are suspended. 

Aqueous ammonia can also behave as a weak base giving hydroxide ions in solution. However, addition of aqueous ammonia to a solution of a cation which normally forms an insoluble hydroxide may not always precipitate the latter, because (a) the ammonia may form a complex ammine with the cation and (b) because the concentration of hydroxide ions available in aqueous ammonia may be insufficient to exceed the solubility product of the cation hydroxide. Effects (a) and (b) may operate simultaneously. The hydroxyl ion concentration of aqueous ammonia can be further reduced by the addition of ammonium chloride hence this mixture can be used to precipitate the hydroxides of, for example, aluminium and chrom-ium(III) but not nickel(II) or cobalt(II). 

Because water is not protonated in these solutions, its addition reduces the concentration of ions, and therefore the electrical conductivity. The conductivity reaches a minimum in solutions containing 97% of acid, but rises on further dilution as a result of the formation of nitrate and hydroxonium ions. ... 

Raman spectroscopy I c.i.so showed that the addition of up to io% of water does not affect the concentration of nitronium ions further dilution reduces the concentration of this species, which is not detectable in solutions containing < 85 % sulphuric acid. The introduction of... 

Ridd - has reinterpreted the results concerning the anticatalysis of the first-order nitration of nitrobenzene in pure and in partly aqueous nitric acid brought about by the addition of dinitrogen tetroxide. In these media this solute is almost fully ionised to nitrosonium ion and nitrate ion. The latter is responsible for the anticatalysis, because it reduces the concentration of nitronium ion formed in the following equilibrium ... 

Hydroquinone [123-31 -9] represents a class of commercially important black-and-white chemical reducing agents (see Hydroquinone,RESORCINOL, AND catechol). The following scheme for silver haUde development with hydroquinone shows the quantitative importance of hydrogen ion and haUde ion concentrations on the two half-ceU reactions that describe the silver—hydroquinone redox system ... 

When equal amounts of solutions of poly(ethylene oxide) and poly(acryhc acid) ate mixed, a precipitate, which appears to be an association product of the two polymers, forms immediately. This association reaction is influenced by hydrogen-ion concentration. Below ca pH 4, the complex precipitates from solution. Above ca pH 12, precipitation also occurs, but probably only poly(ethylene oxide) precipitates. If solution viscosity is used as an indication of the degree of association, it appears that association becomes mote pronounced as the pH is reduced toward a lower limit of about four. The highest yield of insoluble complex usually occurs at an equimolar ratio of ether and carboxyl groups. Studies of the poly(ethylene oxide)—poly(methacryhc acid) complexes indicate a stoichiometric ratio of three monomeric units of ethylene oxide for each methacrylic acid unit. 

A protonic acid derived from a suitable or desired anion would seem to be an ideal initiator, especially if the desired end product is a poly(tetramethylene oxide) glycol. There are, however, a number of drawbacks. The protonated THF, ie, the secondary oxonium ion, is less reactive than the propagating tertiary oxonium ion. This results in a slow initiation process. Also, in the case of several of the readily available acids, eg, CF SO H, FSO H, HCIO4, and H2SO4, there is an ion—ester equiUbrium with the counterion, which further reduces the concentration of the much more reactive ionic species. The reaction is illustrated for CF SO counterion as follows ... 

Since the effluent from a softening unit is usually supersaturated with calcium carbonate at the usually high pH values, it is necessary to reduce the pH to a value that allows the solution to be exactiy saturated for the calcium-ion and carbonate-ion concentrations present. The relationship is... 

In both cases, the carbonate ion concentration increases and eventually equiUbrates in the system, releasing carbon dioxide in the stripping column and thereby reducing product purity. Hence, a small caustic wash tower is employed to remove any carbon dioxide that is Hberated in the stripper. 

Chlorate Analysis. Chlorate ion concentration is determined by reaction with a reducing agent. Ferrous sulfate is preferred for quaHty control (111), but other reagents, such as arsenious acid, stannous chloride, and potassium iodide, have also been used (112). When ferrous sulfate is used, a measured excess of the reagent is added to a strong hydrochloric acid solution of the chlorate for reduction, after which the excess ferrous sulfate is titrated with an oxidant, usually potassium permanganate or potassium dichromate. 

Sodium hydrosulfite or sodium dithionate, Na2S204, under alkaline conditions are powerful reducing agents the oxidation potential is +1.12 V. The reduction of -phenylazobenzenesulfonic acid with sodium hydrosulfite in alkaline solutions is first order with respect to -phenylazobenzenesulfonate ion concentration and one-half order with respect to dithionate ion concentration (135). The SO 2 radical ion is a reaction intermediate for the reduction mechanisms. The reaction equation for this reduction is... 

Whenever insoluble anodes are used, the pH of the plating solution decreases along with the metal ion concentration. In some plating baths, a portion of the anodes is replaced with insoluble anodes in order to prevent metal ion buildup or to reduce metal ion concentration. Lead anodes have been used in acid copper sulfate baths, and steel anodes have been used in alkaline plating baths. 

Use of such constructions that can elongate arc-length and reduce the concentration of ions in the arc plasma and hence enhance the dielectric strength between the parting contacts. 

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