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Molecular formula: N2
Position in periodic table: Group-V A, Period-2nd
Electronic configuration: 2, 5 (1S2, 2S2 2P3)
Atomic number: 7
Atomic weight: 14
Molecular weight: 28 amu
Freezing point:- 210 °C
Boiling point: -196 °C
Nitrogen is found in both free and combined states. It occupies 78.07% by volume.
By heating copper in air:
Firstly, air is passed through lime water and then concentrated sulphuric acid to make the air free from carbon dioxide and moistures respectively. The air contains only nitrogen and oxygen which are passed over the heated copper wire as shown in the figure. Here copper combines with oxygen to make copper oxide and nitrogen gas passes over. This nitrogen can be collected by downward displacement of water.
By burning phosphorous in air:
Nitrogen gas can be prepared by burning phosphorous in air. A crucible with phosphorous is taken and allowed to float on water. Then phosphorous is burnt in crucible is covered with gas jar as shown in figure. The oxygen of the gas jar is consumed during the burning of phosphorous penta oxide is formed. The gas left in the jar is nitrogen.
4P + 5O2 → 2P2O5
By decomposition of compounds containing nitrogen
Like, when dilute solution of ammonium nitrite is heated, nitrogen gas is produced.
NH4NO2→ N2 +2H2O
When the solution of sodium nitrite and ammonium chloride is heated they react together and liberate nitrogen gas.
NaNO2 + NH4Cl → NaCl + H2O +N2
Take a mixture of ammonium Chloride and Sodium nitrate in equivalent amount in a round bottom flask. Some water is added to make the solution of the mixture. Then the delivery tube is fitted with a round bottom flask with the help of a cork. The flask is heated gently with a source of heat. After that gas is produced by the reaction of chemicals and is collected in gas jar by downward displacement of water.
When burning magnesium ribbon is inserted in a jar containing gas, if it burns continuously and forms magnesium nitride, it proves that gas is nitrogen.
Uses of nitrogen
Nitrogen is the seventh element on the periodic table. It is located in period 2 and group 15.
Physical properties on nitrogen are:
Nitrogen is an inert gas which constitutes about 78% by the volume of the atmosphere.
We use nitrogen gas for:
Nitrogen gas is prepare in the laboratory by heating the mixture of amoniumchloride and sodium nitrite in the ratio 1:1. NH4CI + NaNO2 --------> NaCI + N2 + 2H2O