58 PROPERTIES OF ELECTRICALLY CONDUCTING SYSTEMS 



is the more true the more consistent the data are among themselves. In 

 the case of the seven electrolytes in Figure 5, the correspondence with 

 the mass-action law is much more certain. One reason for the better 

 agreement in the case of these electrolytes is their lower ionization, as 

 a result of which errors in the value of the equivalent conductance pro- 

 duce a smaller variation in the mass-action constant. Moreover, in these 

 cases the mass-action law appears to apply to greater total salt concen- 

 trations. In view of the fact that the original experimental results are 

 independent of any considerations as to the applicability of the mass- 

 action law, the conclusion appears justified that in the case of solutions 

 in liquid ammonia the mass-action function approaches a limiting value 

 at low concentrations. 



The total salt concentration at which the deviations from the simple 

 mass-action law become appreciable is the lower, the greater the ioniza- 

 tion of the electrolyte. In this respect solutions in ammonia resemble 

 solutions of the acids and bases in water. The lower the ionization of 

 an acid or a base in water, the higher the concentration up to which the 

 mass-action law appears to hold. From an examination of their results, 

 Kraus and Bray drew the conclusion, however, that the deviations from 

 the mass-action law become appreciable for different electrolytes in 

 ammonia solution at about the same ion concentration. They found 

 that the mass-action function for a number of electrolytes was increased 

 over the limiting value by 5% at ion concentrations lying in the neigh- 

 borhood of 1 X 10" 4 N. It is, however, apparent that in certain cases the 

 ion concentration is considerably greater and in other cases considerably 

 lower than this value. So, for example, in the case of potassium amide 

 this concentration is 2.76 X 10~*, while in that of trinitraniline it is 

 0.22 X 10- 4 . 



We may now consider the values of the mass-action constant for 

 different electrolytes in ammonia solution. The values for the inorganic 

 electrolytes are given in Table XXII 15 (see opposite page) . 



It is apparent, in the first place, that the values of the mass-action con- 

 stant for the different inorganic electrolytes differ considerably. The ex- 

 treme values lie between 0.056 X 10~ 4 for sodium amide and 42 X 10' 4 

 for potassium iodide. The greater number of the salts, however, have 

 ionization constants lying between 21 X 10~ 4 and 28 X 10~ 4 . This varia- 

 tion of the ionization constants for different inorganic electrolytes in am- 

 monia is in striking contrast with the nearly identical ionization of the 

 same electrolytes in water. It should be borne in mind, however, that in 

 aqueous solution the degree of ionization is so high, in any case, that dif- 



18 Kraus and Bray, loc. cit. 



