Liquid molar conductivity

Ionic liquid System Cation Anion(s) Temperature, (X Conduc- tivity (k), mS cm Conduc- tivity method Viscosity (n), cP Viscosity method Density (p), gcm Density method Molar conductivity fAJ, cm iT mor Walden product (An) Ref. 

Table 8.2 lists the conductivities, transport numbers and molar conductivities of the electrolyte A = olc, and ions Xj = t+A for a number of melts as weU as for 0.1 M KCl solution. Melt conductivities are high, but the ionic mobilities are much lower in ionic liquids than in aqueous solutions the high concentrations of the ions evidently give rise to difficulties in their mutual displacement. 

His works concerning the improvement of the method of measurement for the boiling point of liquids (so-called improved Beckman method) and the measurement of molar conductivities of aminosulfonic acids are known as the pioneering works of physical chemistry or solution chemistry of Japan. 

The nature of ion association in non-aqueous liquid electrolytes has traditionally been investigated by measuring the molar conductivity. A, as... 

Molar conductivity measurements are equally applicable to both solid and liquid electrolytes. In contrast, the measurement of current flowing through an electrochemical cell on a time scale of minutes or hours while the cell is perturbed by a constant dc potential is only of value for solid solvents (Bruce and Vincent, 1987) where convection is absent. Because of the unique aspects of dc polarisation in a solid solvent this topic is treated in some detail in this chapter. Let us begin by considering a cell of the form ... 

The conductivity of a conducting liquid is very sensitive to the presence of small quantities of electrolytes. Dilution not only increases the proportion of dissolved electrolyte which forms ions in solution, but also reduces generally the number of ions per unit volume. To negate the latter effect, a molar conductivity A is defined as ... 

Ionic liquids with discrete anions have a fixed anion structure but in the eutectic-based liquids at some composition point the Lewis or Bronsted acid will be in considerable excess and the system becomes a solution of salt in the acid. A similar scenario also exists with the incorporation of diluents or impurities and hence we need to define at what composition an ionic liquid is formed. Many ionic liquids with discrete anions are hydrophilic and the absorption of water is found sometimes to have a significant effect upon the viscosity and conductivity of the liquid [20-22], Two recent approaches to overcome this difficulty have been to classify ionic liquids in terms of their charge mobility characteristics [23] and the correlation between the molar conductivity and fluidity of the liquids [24], This latter approach is thought by some to be due to the validity of the Walden rule... 

Electrolyte junction — A liquid junction is the region of contact of two different -> electrolyte solutions kept apart by a porous -> diaphragm, such as sintered glass or ceramic. At the contact a -> Galvani potential difference appears, which is called -> liquid junction potential (Ej). In the case of two solutions of the same electrolyte, but with different concentrations (c(a) and c(/S)), the potential Ej is defined by the equation Ej = (t+-t-) ln ry, where t+ and t are - transport numbers of the cation and anion, respectively. If the concentration of one of the ions is the same in both solutions, but the other ion differs (e.g., NaCl and KC1), the potential Ej is given by the Henderson equation, which is reduced to the Lewis-Sargent relation for a 1 1 electrolyte Ej = ln, where A (/3) and A (a) are molar conductivities of the electrolytes in the com-... 

Use the Henderson equation to estimate the liquid junction potentials for the following systems assume that the limiting molar conductivities given in table 6.2 can be used to calculate the ionic mobility. 

Ionic liquid system Cation Anion(s) Temperature (K) Conductivity (K), mS cm 1 Conduc- tivity method Viscosity (V), CP Viscosity method Density (Pi, g c 3 Density method Molar Conductivity (A), cm2 Q -1mor7 Walden product (M) Ref. 

The increase in the molar conductivity, corrected for viscosity effects, with increasing I2 content of MI (M = Me4N, Et4N, BU4N, or Na) in I2-DMF solutions and of Nal in I2-DMSO solutions has been attributed to the so-called relay conduction mechanism of 1 ions in I2 solutions."" These results support the proposal made earlier that the lower, but normal conductivities of Nal in liquid I2 are due to the thermal instability of Na I(l2)n- The formation of I3 has been studied spectrophotometrically in MeOH, Pr OH, Bu OH, MeCN, and DMSO" and in mixtures of these solvents both with and without water. 

As the concentration of a solution of an -block metal in liquid NH3 increases, the molar conductivity initially decreases, reaching a minimum at 0.05moldm . Thereafter, the molar conductivity increases, and in saturated solutions is comparable with that of the metal itself Such saturated solutions are no longer blue and paramagnetic, but are bronze and diamagnetic they are essentially metallike and have been described as expanded metals. The conductivity data can be described in terms of... 

In the present work measurements were made of molar conductivity versus concentration of several electrolytes dissolved in a mixed liquid ion exchanger and a diluent of low polarity. 

Figure 23 is a log-log plot of a number of experimental data for CaBr dissolved in different concentrations of the mixed liquid equimolar cation and anion exchanger in toluene. All molar conductivities have been corrected for the viscosity of the medium by the Walden correction... 

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