The ion concentration determination from current-voltage characteristics of electrolytes

Abstract

In the experiment, an electrolytic cell with electrodes of different area was used. To study the current-voltage characteristics, a pulse-based measuring circuit was developed and implemented. It became possible to carry out an experiment with a small average current due to the large duty cycle between the measuring pulses. Such an approach made it possible to neglect chemical reactions in the near-electrode layers of the space charge, and also to obtain reproducible measurement results. Measurements of current-voltage characteristics in 1% KCl solution were carried out. In the experiment, symmetric current-voltage characteristics were obtained. A numerical derivative of I (U) was found. The shapes of the curves I(U) and I (U) were discussed. The calculations are given showing that for a symmetric current-voltage characteristic the current is electrically proportional to the hyperbolic sine. Accordingly, the current derivative is a hyperbolic cosine. A technique for determining the concentration of ions in simple electrolytes is presented. The error of the presented method is 10–12%. The proposed method of measurement makes it possible to obtain current-voltage characteristics without the use of large-size installations containing mercury. Refs 5. Figs 1.