228 



Conductivity of Aqueous Solutions. Part VII. 



In table 88 are given the means of these for each group of nearly equal 

 concentrations, which means correspond to the ionization values given in 

 table 87. In computing these constants the concentration has been 

 expressed in equivalents per liter. In the last line under each substance 

 are given in black type, what are probably the best values for dilute solu- 

 tions, taking into consideration the experimental errors in the more dilute 

 solutions and the deviation from the mass-action law in the more con- 

 centrated ones. 



Table 88. I onisation-constants X 10 6 for ammonium 

 hydroxide and acetic acid. 



It will be noted that at 18 the ionization constants of both substances 

 are considerably less at 0.4 normal than at 0.1 normal, doubtless because 

 of inaccuracy in the assumptions involved the validity of the mass- 

 action law or the proportionality between ionization and equivalent con- 

 ductance. That at the higher temperatures of 218 and 306 the mass- 

 action law holds, at any rate approximately, at moderate concentrations 

 is shown for ammonium hydroxide by these results. This has previously 

 been shown to be true for acetic acid at 218 by Noyes and Cooper. 

 Their values of the constant (18.2 and 1.69 X 10 _c ) also agree well with 

 mine (18.4 and 1.72 X 10 -6 ). This is especially true when the somewhat 

 different manner of correcting for the conductance of the water is con- 

 sidered; thus their value at 218 when corrected as described in section 

 79 of this part becomes 1.72. 



