Debye-Huckel-Onsager theory

See - conductance, - conductivity cell, -> conductometry, - Debye-Falkenhagen effect, -> Debye-Huckel-Onsager theory, - electrolyte, -> ion, -> Kohlrausch square root law, - mass transport. 

Debye-Huckel-Onsager equation Onsager equation, - Debye-Huckel-Onsager theory... 

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... 

As the dependency does not include any specific property of the ion (in particular its chemical identity) but only its charge the explanation of this dependency invokes properties of the ionic cloud around the ion. In a similar approach the Debye-Huckel-Onsager theory attempts to explain the observed relationship of the conductivity on c1/2. It takes into account the - electrophoretic effect (interactions between ionic clouds of the oppositely moving ions) and the relaxation effect (the displacement of the central ion with respect to the center of the ionic cloud because of the slightly faster field-induced movement of the central ion, - Debye-Falkenhagen effect). The obtained equation gives the Kohlrausch constant ... 

Falkenhagen effect, -> Debye-Huckel-Onsager theory. Refs. [i] Atkins PW (1994) Physical chemistry. Oxford University Press, Oxford, p 855 [ii] Bockris J OM, Reddy AKN (1998) Modern electrochemistry, vol. 1. Plenum Press, p 520... 

See also -> Huckel equation of electrophoretic mobility, -> Debye-Huckel approximation, -> Debye-Huckel length, -> Debye-Huckel limiting law, -> Debye-Huckel-Onsager theory, -> Debye-Huckel parameter. 

It is a function expressing the effect of charge of the ions in a solution. It was introduced by -> Lewis and Randall [iii]. The factor 0.5 was applied for the sake of simplicity since for 1 1 electrolytes I = c (electrolyte). It is an important quantity in all electrostatic theories and calculations (e.g., - Debye-Huckel theory, - Debye-Htickel limiting law, - Debye-Huckel-Onsager theory) used for the estimation of -> activity coefficients, -> dissociation constants, -> solubility products, -> conductivity of -> electrolytes etc., when independently from the nature of ions only their charge is considered which depends on the total amount (concentration) of the ions and their charge number (zj). 

Aeq at infinite dilution. For the theoretical explanation see -> Debye-Huckel-Onsager theory. 

One caimot, however, expect the Debye-Huckel-Onsager theory of the nonequilibrium conduction properties of ionic soiutions to fare better at high concentration than the corresponding Debye-Hiickel theory of the equilibrium properties (e.g.. 

The Debye-Huckel-Onsager Theory for Nonaqueous Solutions... 

One point that had long puzzled physical chemists is why the concentration dependence of acids obeys the Debye-Huckel-Onsager theory. Pitts et have now calculated from Conway s theory that... 

Debye-Huckel-Onsager theory — Table. Debye Hiickel-Onsager coefficients of 1-1-electrolytes at 298 K... 

Conductivity equations based on Debye-Huckel-Onsager theory, such as Equation 17.9, cannot predict the conductance maxima. They are valuable tools to study dilute solutions in a concentration range below the maximum where the solvent may be described as a homogeneous medium with permittivity and viscosity of the pure solvent compound. For extension of the transport equations in the theory of transport properties, especially the continuity equation approach, the reader is referred to Ref [183] and the references given there. 

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