APPENDIX L 



TITANIUM TRICHLORIDE SOLUTION: ITS PREPARATION 

 AND STANDARDIZATION 



This reagent is useful for titrating methylene blue solutions. To 

 prepare it, take : 



Titanium trichloride (Merck) 15 per cent solution 9 cc. 



Hydrochloric acid, concentrated 9 cc. 



Boil this mixture on a steam bath until all the H 2 S is expelled. 

 Dilute with oxygen-free water to 3 liters, adding hydrochloric acid 

 to slight excess. Keep the solution in a flask under carbon dioxide 

 or hydrogen. When estimations are to be made, the burette should 

 be filled quickly with the reagent and a little oil added to prevent 

 contact at the top with atmospheric oxygen. The tip of the bu- 

 rette should dip a few centimeters below the surface of the liquid 

 under titration. 



Owing to almost unavoidable changes in the strength of the 

 titanium solution, frequent standardization is necessary. For this 

 purpose a solution of ferric chloride is used with potassium sulpho- 

 cyanate as indicator. The titanium solution is added slowly until 

 the test shows that the ferric chloride is reduced to ferrous. A 

 standard iron solution is made by dissolving 2.9 g. FeCl 3 in 100 cc. 

 water. This corresponds to 1 g. Fe, and 1 cc. corresponds to .01 g. Fe. 

 Not more than 10 cc. of this solution should be used for purposes of 

 titration in estimating titanium samples. 



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