70 ANSWERS TO PRACTICAL QUESTIONS 



13. What weight of Nis there in 1O grams of HNO Z ? 



HNO 3 : 1ST : : 10 : x. 

 63 : 14 : : 10 : x. 

 x = 2.2 grams. 



14. Hoiv much sal-ammoniac would be required to 

 make 2O liters of NH Z measured at 25 C. and 744 mm. ? 



Refer to the answer of Question 5. A liter of NH 3 under 

 standard conditions weighs .76 gram. 



First find how many liters of NH 3 at C. and 760 mm. 

 are required to expand to 20 liters at 25 C. and 744 mm. 

 Call the result V. Then 



Each of these weighs .76 gram. Call the result W. 

 Then NH 3 - NH 4 C1 : : W : x. 



17 . ' 107 ..273x744x20x.76 



298 x 760 

 - 107 x 273 x 744 x 20 x. 76 



17x298x760 

 x = 85.8 grams. 



15. What is the difference between liquid ammonia and 

 liquor ammonice ? 



Liquid ammonia is the result of condensing the gas by cold. 

 Liquor ammoniae is the commercial name often applied to the 

 solution of the gas in water. 



52 1. Why, in filling the hydrogen gun, do ive use 5 

 parts of common air to 2 of II, and only one part of O to 2 

 ofH? 



Because the air is only oxygen, and hence 5 parts of com- 

 mon air are equivalent to 1 part oxygen. 



2. Why are coal cinders often moistened with H s O be- 



fore using ? 



(See Popular Chemistry, p. 45, note.) 



The H 2 O being decomposed by the heat of the fire increases 

 the combustion. 



