82 PROPERTIES OF ELECTRICALLY CONDUCTING SYSTEMS 

 where y' = 'r~' This e( l ua ^ on gives the value of the specific conductance, 



A 



or the ion concentration, at the minimum point. The value of the ioniza- 

 tion follows from the equation: 



Y' _ 



When m equals 1, we have a limiting case in which Equation 18 reduces 

 to: 



dA A 2 mK 



(21) 



K ft 



rr 



It is evident that since -^ decreases as the concentration increases, the 



tangent approaches a value zero at high concentration. The ionization, 

 therefore, approaches a constant value which may be obtained by writing 

 m = 1 in Equation 11; we have: 



or, neglecting K, 



(22) ^ = D or Y f = YT^- 



The ionization of such solutions, therefore, approaches the value -z . 



as a limit. If an electrolyte has a very small value of K and a relatively 

 large value of D, while the value of m is nearly unity, the conductance 

 will vary only very little with concentration at higher concentrations. 

 This is the case with the cyanides in liquid ammonia, more particularly 

 with the cyanides of gold and silver. The value of m is a little less than 

 unity for the first substance and a little greater than unity for the 

 second. 13 For the ion concentration Cy 1, Equation 11 reduces to: 



and since K may be neglected at this concentration, we have: 

 (23) 



The constant D, therefore, measures the ratio of the ionized to the un- 

 ionized fraction at the concentration CY = 1. We shall see that, for a 



" Kraus and Bray, loc. cit., p. 1360. 



