184 S. E. Moody — Hydrolysis of Salts. 



From these results it appears that hydrolysis of the salt 

 ceases before all the S0 3 radical is removed. 



In another series of experiments similar portions were boiled 

 in an Erlenmeyer beaker with the iodide-iodate mixture until 

 all the iodine visibly liberated in the reaction was expelled, 

 and the precipitate was then filtered, washed, dissolved in 

 nitric acid and treated with barium chloride. The barium 

 sulphate precipitated, filtered off on asbestos, washed, ignited 

 and weighed was found to correspond almost exactly with the 

 SO s radical not removed by hydrolysis . in the previous experi- 

 ments. 











Table IV 





Mean of 



Zinc 







Time 





BaS0 4 



Equivalent entire 



sulphate. 



KI. 



KI0 3 . 



in 



BaCl 2 . 



found. 



of S0 3 . series. 



cm 3 . 



grm. 



cm 3 



hours. 



cm 3 . 



grm. 



grm. grm. 



25 



1-0 



15 



3 

 4 



10 



0-0817 



0*0280 v | 



25 



1-0 



15 



f 



10 



0-0812 



0-0278 1 

 0-0282 f 00280 



25 



1-0 



15 



H 



10 



0-0821 



25 



1-0 



15 



H 



10 



0-0814 



0-0279 J 



From the results of both Table II and Table III it appears, 

 therefore, that zinc sulphate is not completely hydrolyzed in 

 the presence of the iodide-iodate mixture, and the mean per- 

 centage of such hydrolysis is found to be 8013. So it appears 

 that a one-fifth basic sulphate is formed. The basic sulphate 

 contains 5Zn to 1S0 4 and is so definite that from the iodine 

 liberated the zinc content may be calculated with accuracy. 



The reaction of hydrolysis may be expressed by the equa- 

 tion : 



15ZnSO e + 20KI + 4KI0 3 + 1 2H 2 



= 3Zn 5 (OH) 8 S0 4 +12K 2 S0 4 + 24l. 



Of the various metal sulphates mentioned in this paper 

 zinc sulphate is the only one which is not completely hydro- 

 lyzed, more or less easily, in presence of the iodide-iodate 

 mixture. 



