180 S. E. Moody — Hydrolysis of Salts. 



Table VI (continued). 



SnCl 4 . 

 2KC1. 



EX. 



KIO s 



Approx. 

 , Time in N/10 

 minutes. Na 2 S 2 03 



I. 



Sn0 2 

 calcu- 

 lated. 



Sn0 2 

 precip- 

 itated. 



Diff. 



grin. 



grm. 



cm 3 . 





cm 3 . grm. 

 p 



grm. 



grm. 



grm. 



0*25 



1-0 



15 



120 



24-37 



03137 



0-0933 



0-0931 



+ 0-0002 



0*25 



1-0 



15 



120 



24-35 



0-3134 



0-0933 



00931 



+ 0-0002 



0-25 



1-0 



15 



120 



24-34 



0-3133 



0-0932 



0-0931 



+ 0-0001 



0*25 



10 



15 



120 



24-28 



0-3125 



0-0930 



0-0931 



—o-oooi 



0-25 



1-0 



15 



120 



24-31 



0-3130 



0-0931 



0-0931 



±0-0000 



0-25 



1-0 



15 



120 



24-32 



0-3130 



0-0932 



0-0931 



+ 0-0001 



0-25 



1-0 



15 



120 



24-34 



0-3133 



0-0932 



0-0931 



+ 0-0001 



0-25 



1-0 



15 



120 



24-33 



0-3132 



0-0932 



0-0931 



+ 0-0001 



These results recorded in A show that stannic chloride is 

 completely hydrolyzed in the presence of the iodide-iodate 

 mixture, and that the iodine liberated on boiling is a measure 

 of the tin present. 



The results given in B show that at the temperature of the 

 room complete hydrolysis is also effected by removing from 

 the sphere of action the iodine which at first appears and 

 allowing the mixture to stand two hours before the final 

 titration. 



Cobalt. 



"When cobaltous sulphate is boiled for a considerable time 

 with the iodide-iodate mixture, it is hydrolyzed with the libera- 

 tion of iodine in amount indicating that the following equation 

 shows the character of the initial reaction. 



3CoS0 4 + 5KI + KIO s + 3H 2 = 3Co(OH) 2 + 3K 2 S0 4 + 6l 



Under the conditions of the experiment potassium iodate is 

 present in excess and exerts an oxidizing influence upon the 

 cobaltous hydroxide, thereby forming black cobaltic hydroxide 

 as follows : 



6Co(OH) 3 + KI0 2 + 3H 2 = 6Co(OH) 3 + KI 



After filtering and washing this precipitate and dissolving 

 it with nitric acid, no 'precipitate was obtained with barium 

 chloride and this solution. This evidence goes to show that 

 the hydrolysis was complete. 



The standard of my solution was found by depositing me- 

 tallic cobalt upon a rotating platinum crucible as the cathode, 

 3 grms. of ammonium sulphate being used as the electrolyte 

 for 25 cm3 of the solution of cobaltous sulphate diluted with 

 25 cmS of water, using one ampere for current and continuing 

 thirty minutes. The following table shows these results : 



