Polarization in Electrolytic Solutions. Part II. Measurements

Abstract

The object of the present investigation was to supply material for testing the theory given in the preceding paper. Therefore, the ``polarization capacitance'' and the ``excess resistance'' of electrolytic solutions were measured over wide ranges of frequency and concentration, and for different plate distances. Also the material of the electrodes was modified, and some temperature coefficients were measured. After the general introduction (Sec. I) the method used is described in Sec. II; it is essentially a Jones bridge method, with suitable modifications. In Sec. III the cell is described. Section IV deals with the general scope of the measurements and with the procedure in performing them. The range of frequencies was, as a rule, from 18 to 18,000 cps; the molar concentrations varied from 10⁻⁴ to 10⁻² g‐eq/liter. In addition to solutions of KCl and MgSo₄, conductance water was investigated. Electrodes of Al, Ni, Au, and Pt were used. In Sec. V a survey of the results, independent of any theory is given. Finally, in Sec. VI the results are compared with those of the theory, by analyzing completely several series of measurements referring to water and KCl solutions. A quantitative agreement can be realized, if (a) the effect of the solvent is taken into account, and if (b) it is admitted that there are, in ``conductance water,'' ions of considerably (about 100 times) lower mobility than the ordinary electrolytic ions. With these assumptions the concentrations and the mobilities of the ions can be determined. Finally, the rate constants which are characteristic of the presented theory can be evaluated.