244 PROPERTIES OF ELECTRICALLY CONDUCTING SYSTEMS 



2 liters. As may be seen from the table, the value of i for tetramethyl- 

 ammonium iodide in the neighborhood of 0.01 N is approximately 1.50, 

 while that for sodium acetate is even higher than that of tetramethyl- 

 ammonium iodide, being 1.75 at V = 41.8. 



Phenol has a dielectric constant of 9.68 and the high values obtained 

 for i are unexpected. The conductance of solutions of tetramethylam- 

 monium iodide in phenol at 45 has been measured by Kurtz. 14a The 

 constants for these solutions are m = 1.28, D = 0.69, K = 2.3 X 10~* 

 and A = 16.67. Solutions of tetramethylammonium iodide in phenol 

 thus exhibit an ionization not very different from that found for solutions 

 of typical salts in other solvents, having a dielectric constant in the 

 neighborhood of 10. While the ionization is marked at the lower con- 

 centrations, the value is much lower than corresponds to the value of i 

 found by Hartung. Thus, at a concentration 0.01 N, the ionization from 

 the conductance values is 0.194 in contrast to 0.48 from freezing point 

 determinations. 



It is evident that there is a wide discrepancy between the values of 

 the ionization as determined by the two methods. It is particularly 

 striking that the values of i found for salts of weak organic acids are 

 higher than those for typical electrolytes. Since phenol is an acid sol- 

 vent, it is probable that a solvolytic reaction takes place when a salt is 

 dissolved in phenol according to the equation: 



PhOH + MX = MOPh + HX. 



If this were the case, we should expect the greatest values of i in the 

 case of salts of weak acids and bases, which would account for the high 

 values found for solutions of tetramethylammonium iodide and sodium 

 acetate. Lacking further experimental material, however, the question 

 must be left open. 



The results obtained from molecular weight determinations indicate 

 that, in solvents of intermediate dielectric constant, the values of y^ 

 approach those of y c at low concentrations. At high concentrations the 



divergence is often great and the variation of the i values depends greatly 

 on the nature of the electrolyte. In solvents of dielectric constant lower 

 than 20, the values of y by the two methods are not in agreement. This 

 is not surprising, since these solutions may be expected to show large 

 divergences from the laws of ideal systems. So far as may be judged 

 from the available material, however, at very low concentrations, y and 



7_ approach a common limit in non-aqueous solutions. The corre- 

 i/ 



" a Kurtz, Thesis, Clark Univ. (1920). 



