Alternating Current Method for the Measurement of Electrical Conductivity and Determination of Concentrations in Aqueous Solutions

A nondestructive alternating-current conductometric method for determination of molar concentrations in aqueous solutions is presented. Complete current–voltage characteristics at 50 Hz were recorded and their S-shaped form was analyzed. Four regions corresponding to ohmic conduction, double-layer charging, Faradaic processes, and diffusion limitation were identified. The initial linear segment provided bulk resistance and conductance, while the capacitive region enabled evaluation of double-layer capacitance. Using the Gouy–Chapman–Stern model, Debye layer thickness was calculated and correlated with electrolyte concentration. Calibration with KCl standards (0.001–1 mol L⁻¹) and application to distilled and drinking water showed agreement with classical conductivity within 5%. The procedure requires simple instrumentation, avoids electrolysis typical for DC methods, and yields information on both bulk and interfacial properties.