Chemical Activity of free and Semi-Combined 



143 



TABLE llo. 



TABLE 116. 



DISCUSSION OF RESULTS. 



There is one difficulty in the study of this problem that must first be 

 pointed out, i. e., the use of a strong alkali solution (half-normal NaOH) 

 with which to titrate the acetic acid formed. This necessarily intro- 

 duces some error, since a difference of 0.1 c.c. in reading the burette 

 would make a difference of over 1 per cent. A more dilute solution of 

 alkali could not be used, since too large a quantity of such a solution 

 would be required. 



As noted in the preliminary paper on this subject, the rate of decom- 

 position of the acetic anhydride is at first very rapid, being almost com- 

 plete at 25 in 5 minutes and nearly three-quarters complete at the end 

 of 10 minutes, then gradually decreasing as the reaction approaches 

 completion. In this respect the reaction differs from similar ones 

 studied, such as the hydrolysis of esters, since in these cases the reac- 

 tions are reversible. Temperature has a marked accelerating influence 

 on the hydrolysis, the velocity of the reaction as a whole and the 

 increase for succeeding intervals of time being much greater at 25 than 

 at 15. 



