Potentiometric Measurements of Hydrogen Ion Concentration in Solutions of Low Dielectric Constant

摘要

This paper deals with potentiometric measurements of hydrogen ion concentration in sdlutions ofp‐toluene sulfonic acid and picric acid in xylene and dioxane. Parallel conductivity measurements complete the data. Apart from usual concentration cells, another type of cell has been tried, namely, one in which the two solutions have not only different concentrations but also different dielectric constants. The chief findings are: (1) Glass electrodes react reversibly with hydrogen ions in organic solvents of dielectric constant as low as 2.3. (2) Acids in such solvents behave essentially as weak electrolytes. (3) Deviations from the simple mass action law are explainable, to a certain extent, on the basis of varying dielectric constant with varying electrolyte concentration. (4) Hydrogen transference numbers and approximate values for absolute ionic radii can be computed from combined conductivity and e.m.f. data.