Conductance, equivalent

The conductivity of a solution containing 1 gram equivalent of solute when measured between two large parallel electrodes at a distance of 1 cm apart is called the equivalent conductivity A. 

See chemical equivalent, equivalent conductivity The specific conductance multiplied by the volume (ml) which contains 1 g equivalent of the electrolyte. 

In the case of small ions, Hittorf transference cell measurements may be combined with conductivity data to give the mobility of the ion, that is, the velocity per unit potential gradient in solution, or its equivalent conductance. Alternatively, these may be measured more directly by the moving boundary method. 

While the result should not have very exact physical meaning, as an exercise, calculating the f potential of lithium ion, knowing that its equivalent conductivity is 39 cm /(eq)(ohm) in water at 25°C. 

Table 8.35 Equivalent Conductivities of Electrolytes in Aqueous Solutions at...

TABLE 8.36 Conductivity of Very Pure Water at Various Temperatures and the Equivalent Conductances of Hydrogen and Hydroxyl Ions... 

The equivalent conductivity of an electrolyte is the sum of contributions of the individual ions. At infinite dilution A° = A° -f A, where A° and A are the ionic conductances of cations and anions, respectively, at infinite dilution (Table 8.35). 

The specific heat of aqueous solutions of hydrogen chloride decreases with acid concentration (Fig. 4). The electrical conductivity of aqueous hydrogen chloride increases with temperature. Equivalent conductivity of these solutions ate summarized in Table 8. Other physicochemical data related to... 

Critical Micelle Concentration. The rate at which the properties of surfactant solutions vary with concentration changes at the concentration where micelle formation starts. Surface and interfacial tension, equivalent conductance (50), dye solubilization (51), iodine solubilization (52), and refractive index (53) are properties commonly used as the basis for methods of CMC determination. 

The term equivalent conductance A is often used to describe the conductivity of electrolytes. It is defined as the conductivity of a cube of solution having a cross-section of one square centimeter and containing one equivalent of dissolved electrolyte. 

The previous definitions can be interpreted in terms of ionic-species diffusivities and conductivities. The latter are easily measured and depend on temperature and composition. For example, the equivalent conductance A is commonly tabulated in chemistry handbooks as the limiting (infinite dilution) conductance and at standard concentrations, typically at 25°C. A = 1000 K/C = ) + ) = +... 

Aquivalent, n. equivalent, gesetz, n. law of equivalents, -gewicht, n. equivalent weight, combining weight, -leiffilhigkeit, /. equivalent conductivity, -verhaltnis, n. equivalent proportion ratio of equivalents. 

It has already been mentioned that in an aqueous solution of KC1 at a concentration of 3.20 X 10-6 mole per liter, the equivalent conductivity was found to have a value, 149.37, that differed appreciably from the value obtained by the extrapolation of a series of measurements to infinite dilution. We may say that, even in this very dilute solution, each ion, in the absence of an electric field, does not execute a random motion that is independent of the presence of other ions the random motion of any ion is somewhat influenced by the forces of attraction and repulsion of other ions that happen to be in its vicinity. At the same time, this distortion of the random motion affects not only the electrical conductivity but also the rate of diffusion of the solute, if this were measured in a solution of this concentration. 

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... 

Thus the actual mobility of an ion, in centimeters per second, is obtained by dividing the equivalent conductivity by the faraday. Some values of mobility are given in Table 3. 

Fig. 28. Values of C J8 from Table 4 plotted against the equivalent conductivity at 18°C.

In Figs. 31 and 32 the ordinates give the equivalent conductivity of HC1, each point being the result of a series of measurements extrapolated to infinite dilution.1 For comparison with similar diagrams given in a later... 

Figs. 31 and 32. Abscissas give the mole fraction of water, ordinates give the equivalent conductivity of HC1. 

Ensure a maximum total solids of 20 ppb TDS (or equivalent conductivity) for once-through and sub- and supercritical boilers, 2 ppm TDS for industrial boilers. 

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