Summary of Nitrogen and Its Compounds

Nitrogen
  • Chemical symbol: N
  • Atomic number: 7
  • Discovered by: Daniel Rutherford in 1772
  • Name origin: Suggested by Jean-Antoine- Claude Chaptal as nitrogène; also known as azote in several languages (Greek for 'no life').
Properties and Occurrence
  • Lightest member of group 15 (pnictogens) in the periodic table.
  • Present in 78% of Earth's atmosphere as dinitrogen (N2), a colorless and odorless gas.
  • Essential for life, found in amino acids, nucleic acids, and ATP.
  • Human body contains 3% nitrogen by mass, the fourth most abundant element.
Nitrogen Cycle
  • Describes movement of nitrogen between air, biosphere, and organic compounds.
Industrial Importance
  • Key compounds: ammonia, nitric acid, organic nitrates, cyanides.
  • Strong triple bond in N2 complicates conversion to useful compounds but releases energy during decomposition.
  • Industry uses synthetic ammonia and nitrates as fertilizers, contributes to water system eutrophication.
Production Techniques
  • Industrial gas production: Fractional distillation of air or mechanical means like pressurized osmosis.
  • In laboratory: Reaction of ammonium chloride (NH4Cl) with sodium nitrite (NaNO2):
    NH4Cl + NaNO2
    ightarrow N2 + NaCl + 2 H2O
  • Pure N2 can also be obtained by thermal decomposition of barium azide or sodium azide:
    2 NaN3
    ightarrow 2 Na + 3 N2
Applications of Nitrogen Gas
  • Used as inert atmosphere in food packaging (E number: E941), in incandescent light bulbs, and in fire suppression systems.
  • Reduces fire hazards in aircraft fuel systems and tire inflation.
Liquid Nitrogen
  • Cryogenic refrigerant used for preserving biological materials, cooling laboratory equipment, and industrial applications (approx. −200 °C).
Ammonia
  • Primary inorganic material; 85% used in synthetic fertilizers.
  • Produced via Haber-Bosch process:
    N2 + 3H2
    ightarrow 2NH3
  • High pressure, low temperature, and active catalysts favor ammonia synthesis.
Hydrazine
  • Used for its high boiling azeotrope with water known as ‘hydrazine hydrate’ (64% composition).
  • Manufactured by oxidizing ammonia or urea with agents like sodium hypochlorite (Raschig Process).
Nitric Acid
  • Processed using the Ostwald method, converting ammonia to nitric oxide and then to nitric acid:
    1. NH3
      ightarrow NO
    2. NO
      ightarrow NO2
    3. NO2 + H2O
      ightarrow HNO3
  • Major applications include fertilizers and industrial chemicals.