Section 98. Summary. 2jp 



156, its ionization-constant can be calculated by the integrated equation 

 given above. Such a calculation leads to a value of 12 X 10~ 6 at 218 ; 

 and from this and the ionization-constant of water determined by Sos- 

 man (section 86, Part VII) the hydrolysis (Chso 4 /Cso 4 ) of potassium sul- 

 phate at 0.002 normal at 218 is found to be 0.04 per cent. Though these 

 values are to be regarded only as rough estimates, yet they show that the 

 hydrolysis of potassium sulphate is insignificant under these conditions. 

 Finally it may be mentioned that this value of the ionization-constant 

 would signify that in a 0.002 normal sulphuric acid solution at 218 the 

 secondary ionization (Cso 4 /Chso 4 ) amounts to only 1.3 per cent. 



98. SUMMARY. 



In this article have been presented the results of conductance measure- 

 ments with dilute solutions of nitric, sulphuric, and phosphoric acids, 

 potassium hydrogen sulphate, and barium hydroxide at 25 or 28 inter- 

 vals between 18 and 156, and with solutions of nitric, hydrochloric, and 

 sulphuric acids at 218, 2G0, and 306. The final values will be found 

 in tables 108 and 109, section 95. Some of these have been plotted in 

 figure 18, on page 266. 



The general conclusions to be drawn from the results may be stated 

 as follows : 



The equivalent conductance of completely ionized acids, which has 

 already been shown by Noyes and Cooper to approach that of neutral 

 salts up to 218 continues to do so up to at least 306, where, for example, 

 the ratio of that for hydrochloric acid to that for potassium chloride has 

 become 1.27 (instead of 2.91 at 18 and 1.53 at 218). 



The equivalent conductance (A), and therefore also the ionization (y), 

 of hydrochloric acid, nitric acid, the barium hydroxide change with the 

 concentration (C) according to the same empirical law, C(A A) = 

 K(CA) n or C(l y) = K(Cy) n with n approximately 1.5, as holds 

 true in the case of salts. The ionization of all of them (see tables 114 

 and 115, section 97) decreases steadily with the temperature, and up to 

 156 by about the same amount as with neutral salts of the same ionic 

 type; the same is true of hydrochloric acid up to 306, but the ionization 

 of nitric acid between 218 and 306 decreases much more rapidly, so 

 that it is only 33 per cent instead of about 60 per cent in 0.08 normal 

 solution at 306. 



Dilute nitric acid at 218 and 306 exhibited a somewhat remarkable 

 chemical behavior, in that it sometimes underwent almost complete decom- 

 position, apparently into nitrogen (or nitrous oxide), oxygen, and water, 

 when this decomposition once got started through the presence of a minute 



