Comparative analysis of methods for determining the parameters of the measuring transducer of a contact conductometer

Abstract

The issues of increasing the accuracy of contact conductometers are considered. The main sources of error of the primary measuring transducer of the contact conductometer are described, which include the solution resistance, as well as the polarization resistance and the capacity of the electric double layer, which characterize the electrochemical processes on the electrodes of the transducer. Methods for determining the specified parameters affecting the impedance of the primary measuring transducer are proposed. The first method is based on the analysis of the amplitude-frequency characteristics of the active impedance component of the conductive constant cell of the contact conductometer filled with a solution. The second method is based on determining the active component of the impedance of the solution at the resonance frequency, at which the reactive component of its impedance is equal to zero. A third method is proposed, in which the active component of the solution impedance is determined at three different frequencies. It is noted that the second method can reliably determine only the active resistance of the solution. Constant cells are determined by the first and third methods in the same frequency range; the second method uses a frequency several times higher than the upper limit of this frequency range. It is shown that the results obtained by the second and third methods practically coincide and differ significantly from the constant cell found by the first method.