Section /oj. Hydrolysis of the Ammonium Salt. 293 



Table 123 contains the data for the ammonium salt in the presence of 

 an excess of the free acid or base. The first five columns are self-ex- 

 planatory. 



The sixth column contains the uncorrected specific conductance X 10 a 

 of the solution in reciprocal ohms obtained by multiplying the observed 

 conductance by the conductance-capacity and by 10. 



The seventh column contains the corresponding specific conductance 

 corrected by subtracting that of the water and in some cases the small 

 estimated increase due to progressive contamination during the period of 

 the measurement (see section 101). 



The eighth column headed "Salt in solution" contains the same values 

 after correcting them for the specific conductance of the ionized ammo- 

 nium hydroxide, when this was present in excess. (The conductance 

 due to the ionized acid when it was in excess was entirely inappreciable.) 

 This conductance (l b ) was computed by the equations: 



Coh = ^ = ^ ; and Lb = 10 3 Con (Anh + Aoh) 



Cnh 4 ty 



in which Kb is the ionization-constant for ammonium hydroxide, Cb the 

 excess of it present, and C is the concentration of the salt and y its degree 



of ionization. 



The ninth column gives the concentration (C ) at which the salt in 

 water alone has the same specific conductance as that (given in the eighth 

 column) of the salt in the presence of the acid or base; this concentration 

 C was calculated by the empirical relations between C and l given on the 

 preceding page. 



The last column contains the values of the percentage hydrolysis 

 (100/? ) of the salt in water alone at the concentration C . These values 

 have been computed by means of the equation : 



, C C Cb ( C C ) 



C Cb 2 (C C) 

 in which C represents the concentration of the salt in the mixture and C B 

 that of the added base (or acid). This equation results from combination 

 of the two equations : 



c.(i K)=c(i h) 



(C h o y = Ch(Ch + CB) 

 in which h represents the hydrolysis of the salt in the presence of the 

 excess of base (or acid). The first of these, which states that the con- 

 centration of the unhydrolyzed portion (which is equal to the sum of 

 the concentrations of the ions and the un-ionized salt) is the same in the 

 two cases, is a consequence of the definition of C . The second of these 



