Equilibrium constants Equivalent conductivity,

While salt is entering the membrane its electrical resistance falls progressively. If the equivalent conductance A of the salt in the membrane may be regarded as constant, which is consistent with the equilibrium conductance data to be discussed later, integration of the local resistance across the thickness of the membrane leads to... 

How does the cell constant k compare with the geometric value HA obtained from an approximate measurement of the dimensions of your ceU Why is the equivalent conductance Aq so large for an HCl solution How do the slopes of your A versus -Jc plots for strong electrolytes compare with literature values and the values expected from Onsager s theory Find a literature (or textbook) value for the equilibrium constant for HAc ionization. Using this value and Eq. (13), draw a dashed literature/theory line on your plot of log versus -Jm. Are the deviations of your data points from this line reasonable in view of the experimental errors expected in this work What is the limiting factor in the accuracy of your measurements ... 

TPVT titrations of cis-[Co(en)2(H2O)2] and [Co(tren)(H20)2] gave similar results . The equilibrium constant of (12) was approximately 1 in these three ions, so that in dilute solutions (< 10" M) the tetrapositive, binuclear ions will be almost completely dissociated into dipositive hydroxoaqua ions. The last conclusion was confirmed by Feltham-Onsager plots of the equivalent conductance (at 0°C) versus the square-root of the concentration of four salts [Co(NH3)4(H20)(OH)](N03)2 Cr(NH3)4(H2O)(OH)]-(NO,), [Co(NH3)4(H2O)(OH)]Br2 = and [Cr(H2O)d(NO3)3 -F NaOH . The conductivity data were for solutions of concentrations between 10 and 10" M. At these concentrations the Feltham-Onsager plots are linear. All four plots had the typical slope of 1 2 electrolytes which was less than half of the slope of 1 4 electrolytes. 

The equivalent conductivity of a weak electrolyte varies approximately with (Fig. 31.3). Explain this in terms of the equilibrium constant for small degree of dissociation. 

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. 

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 ... 

Fig. 1—Equivalent conductance of tetra-/so-pentyl ammonium nitrate in isotropic p-azoxyanisole at 152°C, (solid line). The equilibrium constant for ion-pair formation Is 2 X 10 m/l. The data is bracketed between calculated values of Eq. [4] for two values of the dielectric constant. The variation of the equivalent conductance with dielectric constant is found in Eq. [8]. (Ref. [3])...

The magnitude of the dissociation constant A plays an important role in the response characteristics of the sensor. For a weakly dissociated gas (e.g., CO2, K = 4.4 x 10-7), the sensor can reach its equilibrium value in less than 100 s and no accumulation of CO2 takes place in the interior layer. On the other hand, SO2, which is a much stronger acid (K = 1.3 x 10-2), accumulates inside the sensor and its rep-sonse time is in minutes. The detection limit and sensitivity of the conductometric gas sensors also depend on the value of the dissociation constant, on the solubility of the gas in the internal filling solution, and, to some extent, on the equivalent ionic conductances of the ions involved. Although an aqueous filling solution has been used in all conductometric gas sensors described to date, it is possible, in principle, to use any liquid for that purpose. The choice of the dielectric constant and solubility would then provide additional experimental parameters that could be optimized in order to obtain higher selectivity and/or a lower detection limit. 

The value of 1/a for nitrogen at 1 atm is 272. Experiments with other gases indicate that the ice point, 0°C, is equivalent to a value of near 273 K. The Kelvin scale is now defined with high accuracy such that the triple point of water (where ice, water and water vapour are all in equilibrium, at 0.01°C) has the temperature 273.1600° on the Kelvin scale. The triple point is more accurately defined than the ice point. On this basis 0°C is 273.15 K. Measurement on this ideal gas scale is best conducted with a constant pressure helium thermometer, although there are small deviations from the absolute scale. A comparison of the four temperature scales discussed above is given in Table 1.1. 

Conversely, if one begins with the anhydrous lithium iodide and exposes the solid to water vapor, as long as the vapor pressure is less than any of the dissociation pressures, no hydrate phase can form. At the lowest dissociation pressure a univariant system is obtained, since upon formation of the hydrate phase there must be three phases in equilibrium. Since the experiment is being conducted at constant laboratory temperature, the pressure must also be constant. Continued addition of water vapor can only result in an increase in the amount of hydrate phase and a decrease in the amount of anhydrate phase present. When the anhydrate is completely converted, the system again becomes bivariant, and the pressure increases again with the amount of water added. The higher hydrate forms are in turn produced at their characteristic conversion pressures in an equivalent manner. 

To illustrate how the superconducting gap is observed experimentally we consider a contact between a superconductor and a metal. At equilibrium the Fermi level on both sides must be the same, leading to the situation shown in Fig. 8.7. Typically, the superconducting gap is small enough to allow us to approximate the density of states in the metal as a constant over a range of energies at least equal to 21A around the Fermi level. With this approximation, the situation at hand is equivalent to a metal-semiconductor contact, which was discussed in detail in chapter 5. We can therefore apply the results of that discussion directly to the metal-superconductor contact the measured differential conductance at T = 0 will be given by Eq. (5.25),... 

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