PRACTICE II 



PREPARATION OF A STANDARD AMMONIA SOLUTION 



Determine, by hydrometer, the specific gravity of concentrated 

 ammonia, and calculate, by the use of the specific-gravity table, 

 the number of cubic centimeters necessary to make 2 liters of ap- 

 proximately one fifth normal ammonia solution. 



Sp.gr.... 



Grams NH 3 per cc 



Grams NH 3 per liter in normal solution 



Grams NH, in 2 liters of 1-5 normal solution 



a 



No. of cc. of cone. NH 3 equivalent to g. NH 3 



Measure out the required amount of concentrated ammonia, add 

 water to make the total volume up to 2 liters, and mix thoroughly. 

 Standardize by titrating 10 cc. of the standard hydrochloric acid 

 with the ammonia solution, using lacrnoid as an indicator. Make 

 three titrations : 



(1) 10 cc. HC1 is equivalent to cc. NH 3 



(2) 10 cc. HC1 is equivalent to cc. XH 3 



(3) 10 cc. HC1 is equivalent to cc. NH 3 



Av cc-XHg 



1 cc. NH 3 is equivalent to mg. N. 



Give reactions in first and second practices, and record the com- 

 putations involved in ascertaining the weight of nitrogen in 1 cc. 

 of the standard ammonia solution. 



