Equivalent conductance theory

Consider now the observed values of the equivalent conductivity for the various species of ions given in Table 2 [disregarding the ions (OH)-and H+, which need special consideration]. If we ask, from this point of view, why such a wide variety of values is found, this must be ascribed to the wide variety in the character of the random motion executed by different species of ions in the absence of an electric field. We shall not go into the details of Einstein s theory of the Brownian motion but the liveliness of the motion for any species of particle may be expressed by assigning a value to a certain parameter for a charged particle in an... 

Assuming infinitely long polyelectrolyte chains, the Manning theory neglects the influence of molar mass on the equivalent conductivity. It could be shown in... 

Debye-Huckel-Onsager theory — (- Onsager equation) Plotting the equivalent conductivity Aeq of solutions of strong electrolytes as a function of the square root of concentration (c1/2) gives straight lines according to the - Kohlrausch law... 

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 ... 

In the thermal conduction theory, such a distribution in general is thought to be caused on condition that the rate of heat transfer from the self-heating fluid filled in a container and placed in the atmosphere under isothermal conditions, through the whole fluid surface, across the container walls, to the atmosphere is far less than the rate of thermal conduction in the fluid. In other words, this condition is expressed UKK A, which is equivalent to that the Biol number lakes a small value. 

Figure 2. Osmotic coefficient and equivalent conductivity A of LiCUAt solution in DMC as the functions of electrolyte concentration c. - experimental values [29, 33], solid line -theoretical prediction from the AMSA theory [13,14].

Theoretical interpretation of the concentration dependence of equivalent conductivity for simple binary mixtures was first presented by Markov and Shumina (1956). It should be emphasized that this theory, even when considering simple structural aspects, represents rather a method of interpretation of the experimental data than a genuine picture of the structure of the melt. In molten salts generally only ions and not molecules are present, hence the conception of Markov and Shumina (1956) is to be considered also from this aspect. Their theory is based on the assumption that the electrical conductivity of a mixture of molten salts varies with temperature like pure components. In this respect, general character of the electrical conductivity dependence on composition, indicating the interaction of components in an ideal solution, could be expected. 

This is identical with equation (6.9.1) in the case of 1-1 electrolytes. The predictions of the limiting law for the NaCl system are also shown in fig. 6.10. It is valid for concentrations up to 0.01 M. The success of the theory is clear from this result. First of all, it confirms that plots of A against the square root of ionic strength provide a valid route for determining Aq, the equivalent conductance in the limit of infinite dilution. In addition, it explains why the slope of the plot in the dilute solutions regime depends on the nature of the electrolyte. 

The above theory can also be applied to account for the concentration dependence of transport numbers, especially in dilute solutions. Since the transport number can be defined as a ratio of the equivalent conductance of the given ion to the total ionic conductance (equation (6.7.6)), it is clear that a non-linear relationship can be derived describing the concentration dependence using equations (6.9.23) and (6.9.24). 

The classical theory of conductance as proposed and supported by Arrhenius and his followers is outlined briefly in Chapter 3. It will be recalled that according to that theory the decrease of the equivalent conductance, A, of an electrolyte with increasing concentration was considered to be due to a decrease in the relative number of ions, the proportion being given by the ratio... 

Classical electrolyte theories were developed to explain equivalent conductance of electrolyte solutions and not mobility of sample ions at infinite dilution. In essence, such theories describe the electrophoretic behavior of the electrolyte and not the sample ions. Theories for the mobility of sample ions are difficult to formulate and are only poorly developed at present. A simple extension of classical electrolyte theories to electrophoretic mobility for ions of finite size, allows the derivation of Eq. (8.4) [32]... 

In the previous section we saw the key roles played by the various partial conductivities—or equivalently the transference numbers—in mixed conduction theory. They appear prominently in the integrands of the formulas for open circuit emf emd scaling rate. Thus, if they exhibit any dependences on partial pressure Px2 which is equivalent to Px2 these dependences will have very... 

In part I above, c. Wagner s theory of mixed conduction was reviewed in terms of an equivalent circuit approach. The implications of mixed conduction theory for parabolic scaling of metals in high temperature atmospheres were also detailed. It was pointed out, however, that current interest in mixed conduction theory is no longer motivated by corrosion considerations because far too few systems of practical interest conform to the conditions required for pareibolic oxidation. 

A + BA with that determined experimentally from the slope of the equivalent conductance some values are tabulated in Table 3.5. It is clear that the Debye-Hiickel-Onsager theory accounts satisfactorily for the behavior of A at low concentrations. As the ion concentration increases into regions where Debye-Hiickel theory no longer accurately describes electrolyte activity, there are also severe deviations from (3.30). 

Surf] plot and A refers to the equivalent conductivity of the surfactant counterion at infinite dilution. Models that are more sophisticated are also available for calculating (a i,) from conductivity data at various (T) and ionic strengths these are based on the mass action micellization thermodynamics and the Debye-Hiickel-Onsager conductivity theory [32]. 

Definitions. Define (a) theory of electrolytic dissociation, (b) lattice energy, (c) hydration energy, (d) Faraday s laws, (e) iaday (unit), (f) conduo tivity, (g) equivalent conductance, (h) strong electrolyte, (i) weak electrol)rte. 

---