PRACTICE III 



BLANK DETERMINATION OF NITROGEN IN REAGENTS 

 USED IN DISTILLING 



Place 250 cc. of ammonia-free water in a Kjeldahl flask and con- 

 nect latter in the distillation apparatus shown in the figure on the 

 opposite page. Arrange the 300-cc. Erlenmeyer flask K, contain- 

 ing 10 cc. of the standard hydrochloric acid and about 15 cc. of 

 ammonia-free water, so that the end of the delivery tube / dips into 

 the solution. By disconnecting at D and inserting a funnel in the 

 rubber tube, bring 10 cc. of an alkali solution (1000 g. Greenbank 

 alkali and 25 g. potassium sulfid in 1000 cc. water) into the Kjeldahl 

 flask. Close the pinchcock E, shake the flask thoroughly, and con- 

 nect with the steam generator C. Open the pinchcock E and close 

 A, thus forcing steam through the flask and carrying the liberated 

 ammonia over into the standard acid. Heat the Kjeldahl flask suffi- 

 ciently to prevent condensation of the steam. Distil to a volume of 

 200 cc., add lacmoid, and titrate with the standard ammonia solution. 



(1) Titration .................................................................................... cc. NH 3 



(2) Titration ..................................................................................... cc. NH 3 



Av .................................................................. ......................... cc. 



State correction in cubic centimeters of standard ammonia solution. 

 What does this mean, and how is it to be used ? 



