Revisit the classical theories of the conductance of unassociated electrolytes. Is there reality in relaxation?

Abstract

The experimental results of the ionic conductance of the electrolytic solution can be explained without the use of relaxation until almost 2M concentration of the NaCl solution within 97% agreement with two parameters: the hydrated ion radii for cations and anions. No other fitting parameters were introduced, and no ion association was assumed. The theory is based on a newly introduced electrochemical potential that incorporates the interaction between ions and fluctuations in electrolyte concentration in the nanosized region. It was found that the concept of local chemical potential, fluctuation in the nanosized area, and symmetry of the system are closely related to the Boltzmann distribution of ions. Extending the concept of a local chemical potential to the case of an external field, the derived ionic mobility automatically includes the effect of electrophoresis. The so-called electrophoretic retardation was found to be equivalent to the shielding effect of the external field. Relaxation bears a minor effect and may contribute to the ion transport of electrolytic solution at most 3%, if exists.