Nitrogen

Nitrogen is an unreactive non-metal which exists in gaseous state, (N2).

It has triple bonds between the two atoms in a molecule.

In a free state: it occupies about 78% the volume of the air.
In a combined state: it is found in form of nitrates and oxides

Laboratory preparation of Nitrogen

It can be prepared from the air:

Main procedure

1. The pure air is passed through concentrated sodium hydroxide to remove carbon dioxide
NaOH (aq)+ CO2(g) → NaHCO3 (aq)
2. The oxygen is removed by passing the mixture over heated copper turnings in combustion tube.
The brown in color copper turns to black copper (II) oxide.
2Cu (s) + O2(g) → 2CuO(s)

The remaining components of air mainly are noble gases which are difficult to remove by any chemical means.
But because they are inert in all chemical reaction we assume the only nitrogen is remained though it is impure.
The gas so formed can be collected over water.

PROPERTIES OF NITROGEN

(a) Physical properties of nitrogen

  1. It is colourless, odourless and tasteless.
  2. It is slightly soluble in water
  3. It has a boiling point of -196⁰C.
  4. Pure nitrogen is lighter than air.

(b) Chemical properties of nitrogen

  1. Nitrogen is relatively unreactive due to the presence of triple bonds which require a lot of energy to break during chemical reaction, however at higher temperatures it reacts with metals to form their nitrides.
    3Mg +N2 →Mg3N2
    2Al + N2 → 2AlN
  2. In the presence of finely divided iron catalyst, nitrogen at moderate temperature and high pressure combines with hydrogen gas to form ammonia gas.
    N2 + 3H2 → 2NH3

Uses of nitrogen

  1. Manufacture of ammonia in Haber process.
  2. It is filled in the light bulbs to give the inert atmosphere, preventing air to combine with a hot filament.
  3. As a refrigerant.
  4. It is used in the manufacture of nitric acid.
  5. It used in the manufacture of nitrogeneous fertilizers eg. CAN, DAP, ASP, UREA.
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