S. E. Moody — Iodides and Iodates. 379 



Art. XXXV. — The Hydrolysis of Salts of Ammonium in the 

 Presence of Iodides and Iodates • by Seth E. Moody. 



[Contributions from the Kent Chemical Laboratory of Yale Univ. — cxlix.] 



Beuck" has shown that when salts of ammonium are sub- 

 jected to heat they are hydrolyzed and that as the acid is 

 increased, either as a direct product of this hydrolysis, or by 

 addition, further dissociation is inhibited. The decrease in 

 dissociation is dependent upon the increase of the acid, and 

 when sufficient acid is present, further hydrolysis is entirely 

 prevented. The amount of hydrolysis is, however, small under 

 the most favorable conditions. 



It is interesting to discover how rapidly hydrolysis will pro- 

 ceed if the free acid is constantly removed by the presence of 

 a mixture of potassium iodide and potassium iodate, and with 

 this end in view a solution of ammonium sulphate, containing 

 5 grms. to a liter, was prepared with which to carry out subse- 

 quent experiments. The value of the solution was determined 

 by precipitating barium sulphate, and by calculation its equiv- 

 alent in iodine according to the equation 



3H 2 S0 4 + 5KI + KI0 3 = 3K a S0 4 + 3H a O + 6l 



was found to be 0*4773 grm. of iodine to 25 cm3 of the ammo- 

 nium sulphate, upon the supposition that all the sulphate of 

 ammonia can be broken up and that the full amount of sul- 

 phuric acid may be made available for reaction with the iodide- 

 iodate mixture. 



To the solution of ammonium sulphate were added potassium 

 iodide and potassium iodate and the mixture was allowed to 

 stand. At the ordinary temperature of the room little effect 

 was noticed, as shown by the following results : 



Table I. 



(NEU) 2 S0 4 . 

 cm 3 . 



KI. 



grm. 



KI0 3 . 



cm 3 . 



Time 



in 

 hours. 



Approx. N/10 

 Na 2 S 2 3 . 

 cm 3 . 



I. 



grm. 



25 



1-0 



20 



3 



0-25 



0-0031 



25 



1*0 



20 



3 



0-25 



0-0031 



25 



1-0 



10 



19 



0-35 



00044 



25 



1-0 



10 



19 



0-35 



0-0044 



In another series of experiments in which the solution of 

 ammonium sulphate was boiled for three hours in an Erlen- 

 meyer beaker before adding the iodide-iodate mixture, results 

 were obtained which vary with the vigor of the boiling, but 

 which show that small amounts of ammonia are volatilized, as 

 * Dissertation, Giessen, 1903. 



