Ionic concentration, total

Bjemim parameter. The virial series is an expansion in the total ionic concentration c at a fixed value of... 

Ionic conductors arise whenever there are mobile ions present. In electrolyte solutions, such ions are nonually fonued by the dissolution of an ionic solid. Provided the dissolution leads to the complete separation of the ionic components to fonu essentially independent anions and cations, the electrolyte is tenued strong. By contrast, weak electrolytes, such as organic carboxylic acids, are present mainly in the undissociated fonu in solution, with the total ionic concentration orders of magnitude lower than the fonual concentration of the solute. Ionic conductivity will be treated in some detail below, but we initially concentrate on the equilibrium stmcture of liquids and ionic solutions. 

Total Salinity. The salinity control of oil-base mud is very important for stabilizing water-sensitive shales and clays. Depending upon the ionic concentration of the shale waters and of the mud water phase, an osmotic flow of pure water from the weaker salt concentration (in shale) to the stronger salt concentration (in mud) will occur. This may cause a dehydration of the shale and, consequently, affect its stabilization. 

Direct measurement of conductivity is potentially a very sensitive procedure for measuring ionic concentrations, but it must be used with caution since any charged species present in a solution will contribute to the total conductance. 

Fabiato, A. (1988). Computer programs for calculating total from specified free or free from specified total ionic concentrations in aqueous solutions containing multiple metals and ligands. Method. Enzymol. 157 378-417. 

We shall write (p) and (q) for the membrane surface layers adjacent to solutions (a) and (p), respectively. Using the equations reported in Section 5.3, we can calculate the ionic concentrations in these layers as well as the potential differences and between the phases. According to Eq. (5.1), the expression for the total membrane potential additionally contains the diffusion potential within the membrane itself, where equilibrium is lacking. Its value can be found with the equations of Section 5.2 when the values of and have first been calculated. 

Even very small amounts of calcium provide a desirable decrease in the Na/Ca ratio. Prior studies indicating potassium chloride totally negates permeability reduction may have utilized water that contained some small amount of calcium ion to measure KC1 solution permeability. A second factor, which might explain the lack of KC1 damage reported in prior studies is a low ionic concentration, especially calcium, in the water used to equilibrate the cores prior to the KC1 tests. 

Sanders J.R. The effect of pH on the total and free ionic concentrations of manganese, zinc and cobalt in soil solutions. J Soil Sci 1983 34 315-323. 

Except when vA = vB, the selectivity coefficient depends on the total ionic concentrations of the resin and the liquid phases. 

The effect of surface potential on interfacial ionic concentration is given by a Boltzmann distribution relating the total solution concentration to that at the interface. For charged, amphiphilic species, binding constants replace these ionic concentrations, and the expression... 

Mitra and Prakash, 1957). If we look at data concerning the pair K-Ca, it is apparent that Ca is favored in the montmorillonite at 25°C and this segregation is accentuated as temperature rises above 50°C. Increases of total ionic concentration in the fluid also favors calcium retention. During burial where temperatures are higher and fluids more saline, one would expect to produce calcic montmorillonites which would be stable well above 100°C if their stability is that of calcic beidellite. Again, the deductions based upon laboratory experiments do not appear to agree with observations on natural minerals. 

The exact value of the dissociation constants which should be used depends on the total ionic concentration and consequently, the constants used for milk are approximate. The following values are generally used ... 

We shall find it convenient to let c (x, t) represent the local total ionic concentration, defined by... 

Recall that ct(x) and n(x) are the local total ionic concentration and the local ionic strength, respectively. Moreover we can argue, as we did in Sect. 4.2, that each Jj(x) must be independent of x and that all these terms must equal zero, except (x) which equals the constant — i/ZyAF. Hence... 

Because the right side of eqn. (86) is a positive constant, it follows that the total ionic concentration, ci is a linear function of distance, as shown in Fig. 23. By integration of this equation, one can readily show that... 

Equation 14.1 contains derivatives of both the concentration and electrical potential, and requires both quantities to be known as a function of position in the membrane so as to predict the flux. To simplify matters, Goldman proposed the approximation that the electric field across the membrane be considered constant (i.e., the electric field is not affected by the presence of ions in the membrane). Under these conditions, the electrical potential gradient reduces to E=—d

applied potential and h is the membrane thickness. This approximation is appropriate for membranes that are relatively thin compared to the Debye length. This is not the case for the skin, even when heat-separated ( 100 pm) or dermatomed ( 0.5 mm). This approximation is also reasonable when the total ion concentrations on both sides of the membrane are equal. However, this is rarely the case in iontophoresis for which the applied ionic concentration is typically much less than that subdermally. 

Fernandez-Sanjuro, M. J., V. Fernandez Vega, and E. Garcia-Rodeja. 1997. Atmospheric deposition and ionic concentration in soils under pine and deciduous forests in the river Sor catchment (Galicia, NW Spain). Science of the Total Environment 204 125—134. 

Notation o=e1ectrical conductivity, ic-real relative permittivity, subscripts mix, f and p denote soil-flu id mixture, fluid, and particle, respectively, /-ionic valence, c-ionic concentration, u=ionic mobility is, F =96485.3 C/mol is Faraday s constant, TDS= total dissolved salts in [mg. L], n=porosity, p=density, =surface conduction, S,=specific surface, a=degree of saturation, m=cementation factor, Gv=volumetric water content... 

Equations (3) or (4), with refinements as necessary for "local field" effects, are an appropriate and useful basis for discussion of various models of non-conducting solutions of biological species considered in I. In many cases, however, solutions of interest have appreciable ionic concentrations in the natural solvent medium and the polymer or other solute species may also have net charges. Under these conditions, the electrical response is better considered in terms of the total current density Jfc(t) defined and expressed by linear response theory as... 

Ions of opposite charge tend to associate into loosely-bound ion pairs in more concentrated solutions, thus reducing the number of ions that are free to donate or accept electrons at an electrode. For this reason, the Nernst equation cannot accurately predict half-cell potentials for solutions in which the total ionic concentration exceeds about 10-3 M. 

Table 1 tabulates literature values for acidity constants of seven amine-Ptn complexes with notations on the temperature, ionic strength, total Ptn concentration, method employed, conditions and other remarks, and the reference number. At least six factors enter into comparing determinations of a single complex. First is the purity of the complex under investigation. Because they rely on chemical shifts of an individual species, NMR methods are less dependent on purity than potentiometric titrations, which are interpreted on the basis of equivalents of added base. Rarely is the raw titration data published, but in one case it is evident from a plot of the data that the titration curve reveals up to about 10% impurity [7], Without knowing whether the impurities are acidic, basic, inert, or even forming during... 

When the ion is hydrated by all the adjacent molecules (it = r — 1), there is a strong lattice-site exclusion effect at high ionic concentrations, since the central site can be available to an ion only when both its first and second neighbors are free of ions (a total of 1 + w 4- w(w — 1) = ia2 + 1 sites). On the other hand, when the hydration number (r — 1) is low, almost any free site can be occupied by an ion, since in this case there is a high chance to find at least (r — 1) free water molecules around a selected site. In the next section it will be shown that there is a strong dependence of the site-exclusion effect on the hydration number and, hence, that specific ion effects can be important in the double layer interactions. 

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