Section 72. Conductance of Ammonium Acetate Solutions. 183 



It will be seen from these results that in case of the salt alone and of the 

 mixture of it with acetic acid the final values both at 18 and 100 are 

 from 0.2 to 0.9 per cent lower than the initial values at the same tempera- 

 tures, showing that in the heating at 156 some change took place by 

 which the conductance was decreased. On the other hand with the mix- 

 tures containing ammonia the final values do not differ much from the ini- 

 tial ones in the case of the 26 milli-normal solution, but are larger than 

 the latter in the case of the 10 milli-normal one by about 0.4 per cent at 

 18 and by about 0.15 per cent at 100 showing that some contamination 

 took place in heating to 100 and that this increased on heating to 156. 



The final data needed for the computation of the hydrolysis and some 

 calculated values derived from them are presented in table 67. The first 

 column gives the temperature, and the next two columns give the concen- 

 trations of the salt and acid or base in milli-equivalents per liter at that 

 temperature. The column headed l m contains the most probable values 

 of the specific conductance derivable from the separate values of table 66. 

 At 18 the means of the "initial" values have been adopted; and the same 

 is true at 100 in the case of the ammonium acetate alone and of the mix- 

 ture of it with acetic acid. In the case of the mixtures with ammonia the 

 mean initial values of the specific conductance were decreased by half the 

 percentage amount at 100, and by the same percentage amount at 156, 

 as the initial differed from the final conductance at 18. At 156 in the 

 case of the salt alone and the mixtures with acetic acid, the specific con- 

 ductance was increased by the same percentage amount as the initial dif- 

 fered from the final conductance at 100. These corrections are based 

 upon the indications of contamination just referred to. 



In the next column of the table under l H a or Lboh is given the conduct- 

 ance of the ammonium hydroxide or acetic acid present in the solution. 

 This conductance has been calculated in the following manner: In the 

 mass-action equation 



= K* or -^ = K A 



L BOH C HA 



(where B represents the ammonium ion or radical and A the acetate ion 

 or radical) we can substitute for Cb or Ca the ratio l ba /a ba of the 

 specific conductance (lba) of the salt to its equivalent conductance 

 (A ba) when completely ionized, and thus obtain in terms of known 

 quantities Coh or Cn, which is the concentration of the dissociated base 

 or acid. Multiplying this by the equivalent conductance (A oB oh or 

 A ha) of the base or acid when completely ionized, we get the specific 

 conductance (lboh of l H a) of the base or acid in the mixture. That is: 



Lboh = -KbCboh A boh - and Lha = -KaChaA ha t 2 The values of 

 - Lba ~ Lba 



A ba employed are those given in table 59. 



