THEORIES RELATING TO ELECTROLYTIC SOLUTIONS 349 



taking place between the solvent and the dissolved electrolyte. But 

 here, again, there are doubtless many instances where interaction between 

 the electrolyte and the solvent or an added non-electrolyte is a primary 

 factor in the ionization process, particularly at higher concentrations. 



5. Recapitulation. In recapitulation, solutions of strong electro- 

 lytes, even at low concentrations, do not conform to the laws of dilute 

 systems. The thermodynamic properties of these solutions can not, 

 therefore, be employed for the purpose of determining the state of the 

 electrolyte in these solutions. The conductance method might be ex- 

 pected to give a measure of the fraction of the ionized and un-ionized 

 molecules present. However, the fact that the relative conductance of 

 the ions of strong acids varies at low concentrations renders the results 

 of the conductance method doubtful. 



The hypothesis that electrolytes are completely ionized up to fairly 

 high concentrations lacks experimental support. The agreement of the 

 hypothesis with the consequences of thermodynamic principles can not 

 be looked upon as lending material support, since thermodynamics can 

 teach us nothing with regard to the molecular state of a system without 

 a supplementary hypothesis which directly or indirectly involves the 

 equation of state. The fact that the law of mass-action is approached 

 as a limiting form in aqueous solutions of weak electrolytes and in non- 

 aqueous solutions of all electrolytes for which reliable data are available 

 indicates that, if strong electrolytes in aqueous solution are completely 

 ionized, this constitutes only a particular case and the general problem 

 still remains to be solved. 



Any theory which undertakes to account for the decreased conduct- 

 ance of electrolytes at higher concentrations, on the assumption that the 

 conductance change is due to a change in the speed of the ions, must 

 likewise account for the fact that, in solvents of low dielectric constant, 

 the conductance passes through a minimum value after which it increases. 

 This point may lie at relatively low concentrations. 



The theories of electrolytic solutions thus far advanced are founded 

 chiefly on observations relating to aqueous solutions. There is great 

 danger, here, that phenomena may be assumed as general which, in fact, 

 are only particular. It is of the greatest importance to analyze the 

 results obtained from a study of the properties of solutions in various sol- 

 vents in order to determine which of these are general, applying to all 

 electrolytic solutions, and which are particular, applying only to solutions 

 in certain solvents or under certain conditions. Aqueous solutions are 

 characterized by the uniformity of the phenomena presented by different 

 electrolytes. In other words, the electrolyte, in aqueous solution, has, 



