18 VETERINARY STATE BOARD 



NITROGEN 



Give (a) the symbol, (b) atomic weight, (c) molecular weight, and 

 (d) describe the properties of nitrogen. 



(a) N. (b) 14. (c) 28. (d) Nitrogen is an odorless, colorless, 

 tasteless gas, neither combustible nor a supporter of combustion. 

 It is distinguisbed by having very little affinity for any other 

 element. Nitrogen is not poisonous, but, being unable to support 

 combustion, cannot sustain animal life. In compounds it is unstable. 



What is the function of nitrogen in the air? Describe a process of pre- 

 paring nitrogen from the air. 

 It serves to dilute the oxygen and has some important function 

 in regard to plant life. 



By burning phosphorus in a confined portion of air, the oxygen 

 of the air unites with the phosphorus and forms phosphorus pen- 

 toxide, P2O5. If the experiment is conducted over water, P2O5 

 unites with the water, forming phosphoric acid, leaving nitrogen in 

 the container. 



Name a preparation of nitrogen. Mention the properties of nitrogen. 



Ammonia, NHg. Properties described above. 



Describe the usual method of preparing laughing gas. Write the 

 equation to show the reaction. 



By heating ammonium nitrate, it breaks down directly into 

 water and nitrous oxide. 

 NH^NOa = N^O + 2H2O. 



Name the oxides of nitrogen. 



Nitrogen monoxide, N2O ; nitrogen dioxide, N^Oj ; nitrogen triox- 

 ide, N2O3 ; nitrogen tetroxide, NjO^ ; nitrogen pentoxide, N2O5. 



Calculate the percentage composition of HNO3. [Atomic weight of 

 N = i4.] 



1 + 14 + 48 = 63, the molecular weight of HNO3. 

 1 -=- 63 = 0.0158, or 1,58 per cent, hydrogen. 

 14 -f- 63 = 0.222, or 22.2 per cent, nitrogen. 

 48 -f- 63 = 0.761, or 76.1 per cent, oxygen. 



Mention two nitrates and give two uses of each. 



Silver nitrate, used in medicine and electro-plating. 

 Sodium nitrate, used in fertilizers and in the preparation of 

 saltpetre. 



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