Nitrogen & Its Compounds

I. Dinitrogen

Nitrogen is a very important part of our atmosphere. It forms 78% of our atmosphere by volume and 75% by mass.

Preparation : We have two types of productions of Nitrogen:

Commercial production : The commercial production of Nitrogen is done by the liquifaction and fractional distillation of air.

Lab production : In lab Nitrogen can be produced by several methods-

I. When aqueous solution of ammonium chloride is treated with sodium nitrite.

NH4Cl(aq)+NaNO2(aq)→ N2(g) + 2H2O(l) + NaCl(aq)

II. Dinitrogen can also be obtained by the thermal decomposition of ammonium dicromate.

(NH4)2Cr2O7 →N2(g) + 2H2O(l) + Cr2O3

III. Thermal decomposition of sodium or barium azide also gives dinitrogen. Nitrogen obtained by this method is very pure.

Ba(N3)2 → Ba + 3N2

II. Ammonia()

Ammonia was detected by Priestley in 1774. It is generally formed by the bacterial decomposition of nitrogenous matter found in plants and animals. We can find it in a very less amount in air and soil.

Commercial production: Ammonia is produced by Haber’s process commercially. In this process we prepare a setup with following optimum conditions:

1. Pressure :200 × 105 Pa or 200 atm(Approx), 2. Temperature : About 700 K & 3. Catalyst : Iron oxide with small amount of K2O & Al2O3.


Under these conditions ammonia is produced by the reaction : N2(g) + 3H2(g) → 2NH3(g)

The catalyst is used to increase the production rate of NH3.

III. Oxides of Nitrogen

Nitrogen reacts with oxygen to form different oxides with different oxidation state

1. N2O -Dinitrogen Oxide or Nitrous Oxide or Laughing Gas:

Oxidation state of Nitrogen: 1

Preparation: It can be produced by heating ammonium nitrate.

NH4NO3 N2O + 2H2O


Properties : 1. Nitrous oxide is a colourless gas.

2. It is a has with sweet taste and pleasant odour.

3. It can create laughter when inhaling in a sufficient amount due to which it is called laughing gas.

4. It is soluble in cold water but not in hot water.

5. Nitrous oxide is heavier than air.

Uses : 1. As propellant, 2. As anaesthetic in minor surgical operations with oxygen

II. HNO3-Nitric Acid

Commercial Preparation(Ostwald Process):

The mixture of ammonia and air when passed over platinum gauze catalyst at 7500C-9000C, then ammonia is oxidised to nitric acid.

4NH3+5O2 – 4NO + 6H2O

By oxidising, the nitric oxide is converted to nitrogen dioxide.

2NO + O2 – 2 NO2

When nitrogen dioxide is cooled and absorbed in water, nitric acid is obtained.

3NO2 + H2O – 2HNO3 + NO

Lab Preparation: In the laboratory, nitric acid is formed by heating the mixture of KNO3 or NaNO3 and concentrated H2SO4 in a glass retort.

KNO3 + H2SO4 – KHSO4 + HNO3

NaNO3 + H2SO4 – NaHSO4 + HNO3

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