PRACTICE XIII 



PREPARATION OF AN AMMONIUM SULFATE SOLUTION 



Weigh out exactly in a weighed crucible the number of grams of 

 chemically pure ammonium sulfate (assuming the salt to be dry) 

 equivalent to 1000 cc. of the standard ammonia solution. Dry in 

 the air bath at 115 to 120 for thirty minutes, cool in a desiccator, 

 and weigh. Dissolve in ammonia-free water in a 500-cc. measuring 

 flask. Dilute to exactly 500 cc. Mix well and transfer to a dry 

 500-cc. bottle. Label and keep stoppered when not in use. 



1000 cc. standard NH 3 contains g. N 



Per cent N in (NH 4 ) 2 SO 4 by theory is 



1000 cc. NH 3 is equivalent to g. (NH 4 ) 2 SO 4 



Before After 



heating heating 



Weight of crucible + (XH 4 ) 2 SO 4 = 



Weight of crucible = 



Weight of (NH 4 ) 2 SO 4 



Per cent dry matter in salt is 



How much of the ammonium sulfate will it be necessary to weigh 

 out in order to have exactly 5 g. of the dry salt ? 



30 



