Abstract
UDC 541.546
DOI https://doi.org/10.5281/zenodo.1053457
A method of computer processing of the results of conductivity measurements for a mix of solutions of two electrolytes differing by specific electrical conductivity is developed. By the measurements of specific conductivity and the temperature, this method allows to define the concentration of separate components. The method is based on approximations of theoretical dependences of the electrical conductivity of electrolytes on the concentration according to the equations of Robinson-Stoks and Kolraush and the referenced data concerning the dependence of conductivity on temperature. In the range of concentrations C ≤ 0.02 M and of temperatures 15–25оС the dependences are well approximated by algebraic multinomials not above the 3rd order. The system of approximated functions describes a three-dimensional area χ = f(C1, C2, t) in which the point corresponds to the result of measurements. The method is checked up by the system NaCl-NaOH and is applicable for solutions of any concentration by dilution of a sample to the required level. Two algorithms of experimental data processing are considered. The simplified algorithm is based on notion of the independence of molar electrical conductivity on concentrations in the diluted solutions. The result of the experimental data processing has a raised systematic error from 1 to 5% in mixtures with the raised contents of alkali. A more exact algorithm is based on the approximation of functions of dilution by the equation of Kohlrausch. The systematic error of the specified algorithm less than 0.05% in the mixtures with the highest electrical conductivity and is commensurable with the sensitivity of the conductivity measuting method.
Keywords: approximation, electrical conductivity, mixed electrolyte, concentration, algorithmic error.