CONDUCTION PROCESS IN ELECTROLYTES 33 



and the hydrogen ions are, therefore, 0.656, 0.984 and 1.972 times that 

 of the chloride ion respectively. In other words, the carrying capacity 

 of the hydrogen ion is 3 times that of the sodium ion and 2 times that 

 of the potassium ion. If the tables of the conductance and of the trans- 

 ference numbers are compared, it will be seen that in the more dilute 

 solutions it is generally true that, for salts having an ion in common, 

 those salts whose ions have greater transference numbers likewise have 

 greater conducting power. 



We now come to an important generalization due to Kohlrausch, 20 

 namely: In a solution of a single electrolyte, the two ions move inde- 

 pendently of each other. Therefore, we may determine the fraction of the 

 current carried by each ion, or, in other words, the conductance of each 

 ion in a given solution, by multiplying the equivalent conductance of 

 the solution by the transference number of the electrolyte in this solu- 

 tion. If this is true, then, in a solution of sodium chloride having a 

 concentration of 0.01 normal at 18, the conductance due to the sodium 

 ion is 101.88 X 0.396 =rA Na = 40.34. Similarly, the conductance of the 



potassium and hydrogen ions under the same conditions is: 



A K = 122.37 X 0.496 = 60.69 

 and A H = 369.3 X 0.833 = 307.63 



In these solutions the conductance of the chloride ion is 61.54, 61.68 and 

 61.67 for NaCl, KC1 and HC1 respectively. The conductance of the 

 chloride ion is thus very nearly the same in equivalent solutions of these 

 electrolytes. It is, however, by no means certain that the conductance 

 of a given ion will in all cases be the same in solutions of different salts. 

 If the transference numbers of an electrolyte are known at a given con- 

 centration, then the conductance of its ions may be calculated. 



4. lonization of Electrolytes. As we have seen, the equivalent con- 

 ductance of a solution, which measures, so to speak, the conducting 

 power of the dissolved electrolyte under given conditions, increases with 

 decreasing concentration and appears to approach a limiting value. The 

 current passing through an electrolyte under given conditions is carried, 

 in the case of the simpler types of salts, by two charged constituents, 

 namely the positive and the negative carriers, which, according to Fara- 

 day, are termed the cation and the anion respectively. The relative 

 amounts of the current carried by the positive and negative ions may 

 be determined by means of transference experiments, which depend ulti- 

 mately upon the concentration changes produced by the motion of the 



"Gottinger, "Nachrichten," 1876, p. 213. 



