Electric charge, molar conductivity-diffusion

Ionic Conductivities in Aqueous Solutions The thermodynamic quantities for ions in solution dealt with in the previous sections could be measured only for complete electrolytes (or for charge balanced differences between ions of the same sign) but not for individual ions. On the contrary, this is not the case for ionic conductivities (and diffusion coefficients, see Section 2.3.2.2). These can be determined experimentally for individual ions from the electrolyte conductivities and the transference numbers. The conductivity of an electrolyte solution is accurately measured with an alternating external electric field at a rate of lkHz imposed on the solution with a high impedance instrument in a virtually open circuit (zero current). The molar conductivity, Ag, can then be determined per unit concentration. Ion-ion interactions cause the conductivities of electrolytes to diminish as the concentration... 

Ionic mobility — Quantity defined by the velocity of an ion moving in a unit electric field (SI unit m2 V-1 s-1). The ionic mobility of ion i (uf) is related to its molar ionic conductivity (A ) by A = zfFui, where Z is the charge number of the ion. The ionic mobility is also related to the -> diffusion coefficient (A) by the Nernst-Einstein... 

You are likely already familiar with many of the simple direct force/flux pair relationships that are used to describe mass, charge, and heat transport—they include Pick s first law (diffusion). Ohm s law (electrical conduction), Fourier s law (heat conduction), and Poiseuille s law (convection). These transport processes are summarized in Table 4.1 using molar flux quantities. As this table demonstrates. Pick s first law of diffusion is really nothing more than a simplification of Equation 4.7 for... 

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