Activity coefficients of single ions. II: The difference between the standard chemical potentials of single ions in N‐methylformamide and water at 25°C

The method for the estimation of activity coefficients of single ions, developed by Alfenaar and De Ligny , was improved by incorporating in it ideas of Buckingham and of Muirhead‐Gould and Laidler. The modified method was successfully applied to the transfer of ions from water to N ‐methylformamide. A crucial point in the application of this method is the availability of data on large ions. In the present work, data on the ferricinium ion, the tetramethyl‐ammonium ion, and the tetrapropylammonium ion were used, in addition to data on alkali metal, halide, the perchlorate, and the perrhenate ions. From the difference between the standard chemical potentials of the chloride ion in water and N‐ methylformamide, obtained in this investigation, the corresponding difference between the standard real potentials, determined by Case and Parsons , and the surface potential of water, the surface potential of N‐ methyl‐formamide was determined.