The results of the study of the electric model of a two-electrode conductometric cell when measuring with alternating current are presented. The proposed model is based on the series connection of two impedances, which describe the near-electrode processes and processes in the volume of the test solution. It allows you to separately evaluate the informative and non-informative parameters of equivalent replacement schemes. The results of a theoretical study of the frequency properties of the near-electrode and volume impedances are presented. Based on them, simplifications of the equivalent cell impedance substitution scheme for the frequency-measuring subbands are proposed. The results of the study of the components of the cell impedance are given. A number of parameters have been determined that allow an experimental assessment of the legitimacy of the application of the electric cell model. Referenc es 30, figures 5.

The object of study is a differential two-electrode conductivity cell with a calculated constant, designed for the practical realization of the unit of length – a meter in national measurement standards of electrolytic conductivity of liquids. The differential cell consists of two tubes of the same diameter but different lengths. The article presents an idealized model for calculating cell constants and determining electrolytic conductivity. The presence of holes for filling the cell, caus-ing a distortion of the uniformity of the current density distribution in the middle of the cell, and a significant dielectric permeability of aqueous solutions lead to significant errors when measuring the resistance of liquid columns. The arti-cle presents mathematical expressions for calculating two types of corrections. First, the correction caused by the dis-tortion of the field uniformity due to the presence of the inlet and outlet holes of the cell. Secondly, the correction caused by the presence of bias currents in aqueous solutions of electrolytes. The appearance of a differential cell based on two tubes with a diameter of 9 mm and a length of 50 and 100 mm, respectively, which is being tested as a part of the national measurement standard of Ukraine, is given. References 7, figures 5, tables 2.

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