Equivalent conductance apparent

Both solvent ions show high equivalent conductivities apparently because a chain conduction mechanism is in operation i . 

Calculate the apparent value of the equivalent conductance A for each of these electrolytes in the conventional units cm2 eq-1 ohm-1. How do the A values of these compounds compare with A0 for simple electrolytes in aqueous solutions ... 

Using the dihydrogen salt, NaH2As03, von Zawidzki2 determined the equivalent conductivity in the presence of N/32 arsenious acid in order to diminish hydrolytic dissociation, and concluded that it resembled the salt of a monobasic acid. At extreme dilutions the equivalent conductivity increased, apparently owing to hydrolysis and oxidation. This view that arsenious acid is essentially a feeble monobasic acid is supported by Thomsen s thermochemical values for the heats of neutralisation of the acid (see p. 140). 

In this equation A is the apparent equivalent conductance of the solution, which is equal to 1000 k/c, where k is the observed specific conductance and c is the stoichiometric concentration of the salt in the solution Ac is the hypothetical equivalent conductance of the unhydrolyzed salt, and Aha is the equivalent conductance of the free acid in the salt solution. It follows from equation (35) that... 

Fig. 6, in which the equivalent conductance of sodium iodide in ethyl alcohol at 25° is plotted as ordinates against the logarithms of the dilution, represents the behavior of many salts in solvents other than water. It will be seen that although the equivalent conductance is apparently approaching a maximum, the latter is much farther removed from the experimentally determined points than is the case with water solutions at corresponding dilutions. 

At low enough concentrations that the surfactant is totally dissolved and unassociated, the apparent equivalent conductivities of sodium 8-phenyl-n-hexadecyl-p-sulfonate ought to be about the same as the equivalent conductivities of sodium dodecyl sulfate (SDS), because they have the same cation and this ion contributes the most (around 51/71 =75%) to the conductivity. It followed that the much larger equivalent conductivities measured in samples six or more months old could be attributed neither to the surfactant alone nor to a surfactant impurity, because they did... 

In methanolic solution, [Rh2(DIPHOS)2] [BF4]2 apparently dissociates into mononuclear [Rh(DIPHOS)]" ions (presumably containing coordinated solvent), as demonstrated by (i) electrical conductance measurements which yielded a slope of — 270 ohm" corresponding to a 1 1 electrolyte (20) for a plot of equivalent conductance vs. Vconcn (ii) P NMR measurements which revealed only a single P signal (d, 2P, 8 80, /Rh-p = 203 Hz) and (iii) measurements on the equilibria for the formation of various 1 1 alkene and arene adducts of [Rh-(DIPHOS)] see below). When base (OMe" or a sterically hindered amine such as triethylamine) was added to a methanolic solution of [Rh(DIPHOS)] an irreversible (i.e., not reversed by addition of acid) yellow to red-brown color change was observed, to yield a new species, [Rh3(DIPHOS)3(OMe)2] (4, A.ax 445 nm, e .ax 3.3 X 10 cm" P... 

The equivalent conductivity at finite dilutions is less than Aoo, not on account of incomplete dissociation but because the motion of each ion in the electric field is interfered with by the others. An approximate correspondence between AyjA and the apparent degree of dissociation determined by thermodynamic methods is fortuitous in the sense that the mechanisms underlying the reduction in activity coefficient on the one hand and the lowering of the equivalent conductivity on the other are different. Conductivity of electrolytes has lost some of the fundamental significance which it appeared to possess in the days of Arrhenius, but it remains an interesting property of one of the most important classes of solutions. 

Tabulated are the equivalent conductances, transference numbers, activity coefficients, densities and partial molar volumes, apparent molar compressibilities, heats of solution and dilution for the rare earth salts in aqueous solution at 25 "C. 

This book (about 800 pp.) is a treatise on the physical chemistry of electrolytic solutions with coverage of both equilibrium and non-equilibrium properties. The book includes tables of values of the equivalent conductance, dissociation constants, transference numbers, diffusion coefficients, relative apparent molar heat contents, activity coefficient, pH values, densities, and activity coefficients for many of the more common inorganic and organic electrolyte solutions. 

Since C is not always easy to measure the apparent equivalent conductance... 

Fig. 3.1. Apparent equivalent conductance, /lapp, of various electrolytes as a function of...

From (3.6) and (3.7) it is apparent that a quantity of basic interest in electrolytic conductance is the ion equivalent conductance at infinite dilution. Ordinary conductance measurements cannot separate the contribution of individual ions. By designing experiments that distinguish between ion migration toward positive and negative electrodes in a current-carrying cell it is possible to measure and A separately. A tabulation of the results of such measurements is given in Table 3.1. ... 

Strong electrolytes. The equivalent conductance of an aqueous solution ofHCl at25°C is 425.13 fi cm fiaraday when the concentration is 2.841 X 10" mole/Iiter, and 418.10 when the concentration is 2.994 x 10 mole/liter. Ao for HCl is 426.16 fl" feraday" . (a) From these data, calculate the apparent degree of ionization of HCl in each of the two solutions. (Suggestion Calculate 1 — a, then a.) (b) Calculate the apparent values of the equilibrium constant for the reaction HCl H+ -I- Cl", (c) What conclusions can you draw from the results of these calculations ... 

Eshova et al. studied the hydrogenation of C02 to formic acid in several solvents in the presence of an equivalent of Et3N using Wilkinson s catalyst. These authors conducted an extensive NMR study into the various decomposition pathways of the catalyst [56]. Apparently, DMSO is capable of rapidly displacing one equivalent of PPh3 on the catalyst a second equivalent is slowly displaced. 

The sensor head is lowered into a monitoring well. Upon contact with any fluid, the float ball is raised and a continuous tone emitted from an audible alarm. When the sensor head contacts the interface between LNAPL and groundwater, the change in conductive properties is detected by the electrical conductivity sensor and a beeping tone is emitted. The distances along the tape at which the two changes in the audible alarm occur are recorded as referenced from a presurveyed point on the lip of the monitoring well. The resultant distance is equivalent to the apparent thickness of the LNAPL in the well. 

This notion of occasional ion hops, apparently at random, forms the basis of random walk theory which is widely used to provide a semi-quantitative analysis or description of ionic conductivity (Goodenough, 1983 see Chapter 3 for a more detailed treatment of conduction). There is very little evidence in most solid electrolytes that the ions are instead able to move around without thermal activation in a true liquid-like motion. Nor is there much evidence of a free-ion state in which a particular ion can be activated to a state in which it is completely free to move, i.e. there appears to be no ionic equivalent of free or nearly free electron motion. 

On the other hand, the mechanochemical solid-state reaction was found to be the most suitable for this purpose. Thus, when the solid-state reaction was conducted for Cgo in the presence of one equivalent or less of KCN under the HSVM conditions for 30 min, a clean reaction took place to give the [2-1-2] fullerene dimer C120 (3) in 30% yield while 70% of Cgo was recovered unchanged (Scheme 2) [20]. It is to be noted that no cyanated fullerene such as 4 was obtained in comparison to the result of a liquid-phase reaction in o-dichloroben-zene (ODCB)-DMF [21]. This is apparently ascribed to the difference in reactivity of the initially formed cyanated Cgo anion with or without solvation. 

---