96 PROPERTIES OF ELECTRICALLY CONDUCTING SYSTEMS 



as we have seen, the value of y is expressed approximately as a function 

 of the concentration by means of Equation 11. As was pointed out 

 above, the constant D is practically independent of the dielectric con- 

 stant, while ra increases and K decreases with increasing values of this 

 constant. As a result, the relative ionization of an electrolyte in two 

 solvents will vary with the concentration in a more or less complex 

 manner, and in two solvents the order of the ionization values may be 

 reversed as the concentration changes. 



The important conclusion to be drawn from the behavior of solutions 

 of electrolytes in different solvents is that the conductance function is 

 of the same general form in all solvents. A single empirical equation 

 is capable of expressing the relation between the conductance and the 

 concentration in all cases, practically within the limits of experimental 

 error. Whether or not this equation represents precisely the relation 

 between the conductance and the concentration is relatively unimportant, 

 so long as the deviations from this equation show no decided systematic 

 trend. In aqueous solutions, the weak electrolytes follow the mass- 

 action law in conformity with the ionic theory. The strong electrolytes, 

 however, do not fulfill this condition. It follows from the foregoing con- 

 siderations that the conductance curve for strong electrolytes in water dif- 

 fers from that of electrolytes in other solvents only as regards magnitude 

 of the observed effects and not as regards the nature of the phenomena 

 involved. Any theory which has to account for the relation between the 

 conductance and the concentration of electrolytes in water must equally 

 account for the relation between these quantities in non-aqueous solvents. 



Various theories have been proposed to account for the change of 

 the equivalent conductance as a function of the concentration in the case 

 of strong electrolytes. The simplest of these is that the degree of ioniza- 

 tion is actually measured by the conductance ratio, in which case it is 

 necessary to account for the change in ionization as a function of the 

 concentration. Unfortunately, a general theory of other than dilute 

 solutions does not exist at the present time. A comprehensive method 

 of treating concentrated solutions is therefore lacking. The problem of 

 equilibrium in a system of charged particles has not been solved, and the 

 question therefore remains open as to whether or not the change in 

 ionization may be accounted for. On the other hand, the assumption 

 may be made that the speed of the ions changes as a function of the 

 concentration, as a consequence of which the conductance ratio does not 

 correctly measure the degree of ionization. Certain writers have as- 

 sumed that typical electrolytes are completely ionized in solution and 

 that consequently the change in the conductance is due entirely to a 



