OTHER PROPERTIES OF ELECTROLYTIC SOLUTIONS 321 



In general, compounds between strongly electronegative and strongly 

 electropositive constituents are electrolytes both in solution and in the 

 fused state. This includes not only salts of strong acids and bases but 

 also salts of weaker acids and bases. Thus, the ammonium salts are ex- 

 cellent conductors both in solution and in the fused state. The same is 

 true of salts of organic bases. Here, however, we find a few marked excep- 

 tions. Thus, the trimethylin halides, (CH 3 ) 3 SnX are 'normally ionized 

 in aqueous solution, but are ionized much less than other typical salts 

 in alcohol and still less in acetone. In nitrobenzene and benzonitrile 

 these salts are not ionized at all, although these solvents have dielectric 

 constants higher than that of alcohol. Finally, these salts are not appre- 

 ciably ionized in the liquid state. 55 It is evident that we have here an 

 extreme case of individuality in an electrolytic substance. 



In many cases, the electrolytic properties of a solution are due to 

 interaction between the solvent and the solute whereby an electrolyte 

 is produced. Thus, the acids are electrolytes in solution but in the pure 

 state they exhibit a very low conductance. Indeed, the acids are electro- 

 lytes only in what may be termed basic solvents; that is, solvents capable 

 of forming salts or salt-like substances on addition to an acid. Ammonia 

 and ammonium salts are typical examples of a solvent and a salt of this 

 type. Solutions of the acids in water and the alcohols probably depend 

 for their electrolytic properties on the formation of similar complexes 

 between the acid and the solvent. 56 When acids are dissolved in non- 

 basic solvents, such as sulphur dioxide or nitrobenzol, the resulting solu- 

 tions exhibit a very low conductance, provided the solvent is quite dry. 

 Doubtless, similar considerations hold for solutions of acidic substances, 

 such as the acid amides in ammonia. 57 So, also, solutions of many 

 organic oxygen and nitrogen compounds in the liquid halogen acids owe 

 their electrolytic properties to the formation of a more or less stable 

 complex between the dissolved substance and the acid solvent. The 

 inorganic bases, while intimately related to the acids from the standpoint 

 of their constitution in aqueous solution, are otherwise to be classed as 

 salts. The -properties which they exhibit are throughout characteristic 

 of salts. 



In general, compounds, in which distinctly electropositive and electro- 

 negative constituents are not present, are not electrolytes; or, at any 

 rate, in a fused state they are relatively poor conductors of the electric 



65 Observations by Mr. C. C. Callis in the Author's Laboratory. 



58 Kendall and Gross, J. Am. Chem. Soc. Jtf, 1426 (1921), have investigated the con- 

 ductance of mixtures of acids with esters, ketones and other acids and have found unmis- 

 takable signs of the formation of compounds. 



57 The acid amides do not conduct in water probably owing to the fact that these 

 substances act as very weak bases in water, whose acidic properties are much greater 

 than those of ammonia. 





