S. E. Moody — Hydrolysis of Ammonium Molybdate. 77 



Ammo- 

 nium 



molyb- 

 date 

 grm. 



0-2000 

 0-2000 

 0-2000 

 0-2000 

 0-2000 

 0-2000 

 0-2000 



KI KI0 3 

 grm. cm 3 . 



10 

 10 

 15 

 10 

 10 

 1.0 

 15 



Table I. 



Time 



in Na 2 S 2 3 

 min. cm 3 . 



1-0 

 1-0 

 1-0 

 1-0 

 1-0 

 1-0 

 1-0 



80 

 100 

 90 

 90 

 90 

 90 

 90 



12-85 

 13-10 

 13-12 

 13-08 

 13-15 

 13-13 

 13-11 



I 



found 

 grm. 



0-1580 

 0-1610 

 0-1614 

 0-1609 

 0-1618 

 0-1615 

 0-1613 



Mean 



of 

 entire 



)■ 0-1609 



the amounts of iodine first found do not indicate correctly the 

 actual degree of hydrolysis. 



In another series of experiments in which the products of 

 distillation were received in a solution of potassium iodide 

 acidulated with sulphuric acid, the amounts of iodine obtained 

 corresponded very closely to the complete hydrolysis of the 

 ammonium molybdate according to the equation : 



3(NH 4 ) 6 Mo 7 24 .4H 2 = l8NH 3 + 2lH 2 Mo0 4 



and the liberation of iodine according to the equation 



2lH„MoO +35KI + 7KIO, = 2lK„Mo0 4 + 21I„ + 2lH O. 



Ammo- 

 nium 



molyb- 

 date 



KI 



KIO3 



Table 



Time 

 in 



II. 



Na 2 S 2 3 



I 



found 



Mean 



of 

 entire 

 series 



grm. 



grm. 



cm 3 . 



min. 



cm 3 . 



grm. 



grm. 



0-2000 



1-0 



15 



80 



22-10 



0-2777 ' 





0-2000 



1-0 



15 



90 



22-40 



0-2815 





0-2000 

 0-2000 



1-0 

 1-0 



15 

 15 



100 

 90 



22*42 

 22-37 



0-2818 

 0-2811 



> 0-280 



0-2000 



1-0 



15 



90 



22-36 



0-2810 





0-2000 



ro 



15 



90 



22-39 



0-2814 





In still another series of experiments the apparatus was modi- 

 fied as in the work previously described,* by inserting between 

 the retort and the receiver a Yoit flask containing a definite 

 amount of standard sulphuric acid, in excess of that necessary 

 to combine with the ammonia set free from the molybdate. 

 The value of the standard acid was obtained from the iodine 

 liberated by the addition of a measured portion of it to an 

 iodide-iodate mixture, and the value of the residual acid after 

 the passage of the distillate was similarly measured. The differ- 



* Loc. cit. 



