Keywords
conductivity cell
electrolytic conductivity
measurement
error
differential method кондуктометрія
кондуктометрична комірка
електролітична провідність
вимірювання
кутова похибка
ди-ференційний метод
How to Cite
Abstract
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, causing 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 article presents mathematical expressions for calculating two types of corrections. First, the correction caused by the distortion 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.
References
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