68 AXSWRRS TO PRACTICAL QUESTIONS 



In the flask, one fifth of the atmosphere was free O, which 

 produces NO a with the NO as soon as this is evolved. In the 

 jar there is no free O. 



4. How much NH 3 can be obtained from 3 {/rams of 

 sal-ammoniac ? 



From the reaction, 2NH 4 Cl + CaO = 2NH 3 + H 2 O + CaCl 2 , we 

 see that for every molecule of NH 4 C1 used we obtain one mole- 

 cule of NH 3 . Hence, 



NH 4 C1 : NH 3 : : 3 : x. 

 53.5 : 17 : : 3 : x. 

 x = .95 + , gram. 



ft. What will be the volume of the NH Z at 2O C. and 

 770 mm. ? 



Taking H as our standard, the density of NH 3 is half its 

 molecular weight, or : ^ , = 8.5. The density of O is 16, and 

 a liter of it weighs 1.43 grams. Hence, a liter of NH 3 weighs 

 -jr xl.43 grams, or almost exactly .76 gram. The volume oc- 

 cupied by .95 gram of NH 3 under standard conditions is hence 



'-153 of a liter, or 1.25 

 .76 



quired volume will be 



'-153 of a liter, or 1.25 liters. At 20 C. and 770 mm. the re- 

 .76 



_293 760 



~273 X 770 ' 



x = 1.324 liters. 



0. How much H 2 O will be formed in the process? 



From the reaction we see that one molecule of H 2 O is 

 formed for two molecules of NH 4 C1. Hence, 



2NH 4 C1 : H 3 O : : 3 : x. 

 107 : 18 : : 3 : x. 



7. How much CaO ivlll be needed ? 



From the reaction we see that one molecule of CaO is re- 

 quired with two molecules of NH 4 C1. Hence, 



