HYDROLYSIS OF UREA HYDROCHLORIDE. 133 



The hydrolysis constant decreases considerably as water 

 is replaced by acetone, the effect being greater than when 

 water is replaced by alcohol. The degree of hydrolysis of 

 M/10 urea hydrochloride at 25° O. was also determined in 

 each of these mixtures. The results are given in Table X. 

 Jci is the rate of hydrolysis of 2*5 per cent, methyl acetate 

 by N/10 hydrochloric acid. k 2 is the rate of hydrolysis of 

 2*5 per cent, methyl acetate by M/10 urea hydochloride. 



7i = — = degree of hydrolysis. 



On account of the small amount of unhydrolysed urea 

 hydrochloride in these solutions the ratio ~ has not been 

 corrected as in the more concentrated solutions. 



Under h (calc.) are given the values for the degree of 

 hydrolysis of M/10 urea hydrochloride calculated from the 

 hydrolysis constants IT, given in Table IX. 



Table X. 



Acetone % 



(vol) 



h x 10* 



k 2 x 10 4 



h 



h (calc.) 









2-60 



2-32 



•893 



•895 



20 





2-39 



2-10 



•879 



•885 



40 





1-90 



1-64 



•863 



•855 



60 





1-42 . 



1-15 



•810 



•785 



80 





1-13 



0-725. 



•642 



•580 



The agreement between the calculated and experimental 

 values of h is satisfactory in all cases except in the mixture 

 containing 80 per cent, acetone. On account of the small 

 value of h for M/2 urea hydrochloride in this mixture, a 

 small error in this determination would produce a relatively 

 large error in IT, and on this account there is more likelihood 

 of a difference between the calculated and experimental 

 values of h for M/10 urea hydrochloride in this solution 

 than in the others. 



In the next series of experiments the solvent was kept 

 constant (60 per cent, acetone) and the concentration of 



