228 PROPERTIES OF ELECTRICALLY CONDUCTING SYSTEMS 



and the values of the ionization functions to be introduced for acid and 

 base are therefore not the values for these ionization functions at ordi- 

 nary concentrations of acid and base, but rather the values approached 

 at very low concentrations. Actually, we do not know the limiting value 

 which the ionization functions approach in aqueous solutions of strong 

 acids and bases. Consequently, conductance measurements with dilute 

 salt solutions remain in doubt so long as the values of the ionization 

 functions remain unknown. It is fairly certain that in the case of salts 

 of weaker bases, such as the silver salts, for example, the conductance 

 must be measurably affected at concentrations below 10~ 3 normal. Ac- 

 cording to Bottger, 3 the ionization constant of silver oxide at 25 is 

 2.5 X 10~ 4 . Assuming for the ionization constant of water the value 

 0.91 X 10~ 14 and assuming that the ionization of the salt is practically 

 complete, we obtain the following values for the hydrolysis of silver 

 salts at 25. 



TABLE LXXXV. 

 HYDROLYSIS OF SILVER SALTS AT DIFFERENT CONCENTRATIONS AT 25. 



C 10- 3 10-* 10- 5 



h 1.9 X10- 4 6.0 X10- 4 1.9 X10- 4 



Cond. inc 5.7 X 10' 4 1.8 X 10' 3 5.7 X 10' 3 



As a result of the replacement of Ag + ions by H + ions in the solution, 

 the conductance is increased approximately in the ratio of one to three. 

 In the third line of the above table are given values of the increase in 

 the conductance due to the hydrolysis of the salt. It is seen that even 

 at 10" 3 normal the conductance of a silver salt is affected to the extent 

 of 0.057%, while in a 10~ 4 normal solution the conductance correction 

 amounts to 0.18%. That the hydrolysis of salts of the weaker bases 

 becomes appreciable at higher temperatures is indicated by the work 

 of Noyes and Melcher 4 with the salts of silver and of barium. In the 

 case of silver nitrate, at higher temperatures, a deposit of silver was 

 formed over the inner walls of the platinum-lined bomb. This pre- 

 sumably was the result of a precipitation of silver oxide, which is unstable 

 at these temperatures and decomposes to metallic silver and oxygen. 



The extent of the hydrolysis of salts of strong acids and bases is very 

 uncertain. At the higher concentrations, these electrolytes appear to be 

 ionized somewhat more strongly than typical salts. Washburn has de- 

 duced the value of 0.02 as the limit approached by the ionization con- 

 stant of potassium chloride at low concentrations. But this value really 



" Bottger, Ztschr. }. phys. Chem. 46, 602~(1903). 

 Noyes, Carnegie Publication, No. 63, p. 94, 



