Section 103. Hydrolysis of the Ammonium Salt. 



295 



that these hydrolysis values are derived from experiments in some of 

 which an excess of acid, and in others of which an excess of base was 

 present, and in which varying quantities of these were added, and that 

 most constant errors would either have been eliminated in the difference 

 in the measurements with the mixture and the pure salt, or would have 

 shown themselves by producing opposite effects when the acid and base 

 were in excess. 



Before calculating the hydrolysis-constant, it is necessary to deter- 

 mine the ionization of the salt at the concentrations in question, and 

 therefore to determine the equivalent conductance A for complete ioniza- 

 tion. To do this the equivalent conductance of the unhydrolyzed part of 

 the salt has been calculated at the three concentrations at which measure- 

 ments were made by dividing the specific conductance as given in table 

 123 by the concentration of the unhydrolyzed part C (l h ) ; and evi- 

 dently it is to this concentration that the so-obtained values of the equiva- 

 lent conductance refer. The values for h used at 0.02 and 0.05 normal 

 were the means given in table 123. The value of h used for the 

 more dilute solution was calculated from these by the mass-action for- 

 mula given below. From these three values of A the values of the three 

 constants n, K, and A in the empirical equation, (AC)" = K(A A)C, 

 were computed. The ionization of the salt was then obtained by dividing 

 the A-values by this value of A . 



Table 121 contains the so-derived values of the equivalent conductance 

 and percentage ionization of the salt. The values of the exponent 11 

 were found to be 1.35 at 0, 1.39 at 18, and 1.35 at 25, thus of about 

 the same magnitude as for ordinary salts. The ionization will also be 

 seen to be about the same as that of other salts of the same ionic type. 



Table 124. Equivalent conductance and ionization of the 

 unhydrolyzed ammonium salt. 



