NEET Chemistry Notes p-Block Elements – Group-15 Elements -Dinitrogen
Dinitrogen
Dinitrogen
Uses
- Liquid N2 is used as refrigerant.
- It is used in the manufacture of HNO3, NH3, CACN2 (calcium cyanamide) and other nitrogenous compounds.
- It is used for filling electric bulbs.
Some Important Compounds of Nitrogen
Ammonia
- Ammonia is covalent. N,atom inNH3 is sp3 hybridised. Due to the presence of lone pair of electrons, it acquires pyramidal shape.
- It is prepared by the following methods.
- Catalyst iron oxide with small amounts of K2O and A1203 is used to increase the rate of attainment of equilibrium.
- NH3is basic in nature, has tendency to form hydrogen bond, therefore soluble in water and form NH4OH or NH3(ag).
- Due to basic nature, NH3 is a good complexing agent and reducing agent, e.g.
- NH3 is used in refrigeration due to its large heat of evaporation and in manufacture of HNO3, NaHC03, ammonium compounds and nitrogenous fertilizers.
Nitric Acid (HN03)
- It was earlier known as aqua fortis. It is prepared by the following processes.
- Anhydrous HNO3 is a colourless fuming pungent smelling liquid. It acquires yellow colour due to its decomposition.
- It has corrosive action on skin and causes painful sores.
- It is very strong acid and form salts on reaction with basic oxides, carbonates, hydroxides etc.
- It acts as a strong oxidising agent.
Oxidising Properties of HN03
- Non-metals such as C, S, P and I2 are oxidised to carbonic acid, §ulphuric acid, orthophosphoric acid and iodic acid respectively.
- NO is absorbed by FeS04 and a dark brown ring of nitroso ferrous sulphate is formed (ring test for nitrates).
- Metals like iron, cobalt, nickel, chromium, aluminium become passive in cone.
- HNO3 due to the formation of a thin protective film of oxide on the surface of the metal.
- HNO3 is used in the manufacture of explosives such as TNT, picric acid, nitroglycerine, dynamite etc., fertilizers, such as NH4NO3, basic Ca(NO3)2 etc., artificial silk, dyes, drugs.
Oxides of Nitrogen
The structures of oxides of nitrogen are given below