Nitrogen dioxide - NO2

What is Nitrogen dioxide?

NO2 is a highly poisonous gas with chemical name Nitrogen dioxide. It is also called Nitrogen (IV) oxide or Deutoxide of nitrogen. It is one of the major atmospheric pollutants that is absorbs UV light and stops to reach it to the earth’s surface.

Nitrogen (IV) oxide is a yellowish-brown liquid in its compressed form or reddish brown gas. Its vapours are heavier when compared to air.

Properties of Nitrogen dioxide – NO2


Nitrogen dioxide

Molecular weight/molar mass of NO2

46.006 g/mol

Density of Nitrogen dioxide

1.880 g/dm3

Boiling Point of Nitrogen dioxide

21.15 °C

Melting Point of Nitrogen dioxide

−9.3 °C

Nitrogen dioxide structure – NO2

Nitrogen dioxide structure

NO2 Uses (Nitrogen dioxide)

  • Nitrogen dioxide is used as an intermediate in the production of nitric acid.
  • Used in the manufacturing of oxidized cellulose compounds.
  • Used as a catalyst.
  • Used as an intermediate in the production of sulfuric acid.
  • Used as an oxidizer for rocket fuels.
  • Used as an nitrating agent.
  • Used to bleach flour.
  • Used as an oxidizing agent.
  • Used in the making of explosives.


  • Thermal properties – Exists in equilibrium dinitrogen tetroxide gas:

    2 NO2 ⇌ N2O4

  • As an oxidizer – Due to the weakness of the N–O bond, NO2 is a strong oxidizer.
  • Hydrolysis reaction – Hydrolysis reaction produces nitrous acid and nitric acid.
  • 2 NO2 (N2O4) + H2O → HNO2 + HNO3

  • It is a negligibly slow reaction at low concentrations of nitrogen dioxide.
  • Formation of nitrites – corresponding nitrites are formed by alkyl and metal iodides.
  • 2 CH3I + 2 NO2 → 2 CH3NO2 + I2

    TiI4 + 4 NO2 → Ti(NO2)4 + 2 I2

Health hazards

Severe exposures of Deutoxide of nitrogen can be fatal. When in contact it causes burning sensation to eyes and skin. When in liquid form it causes frostbite. It is reported to react with the blood to form methemoglobin. When heated to decompose, it releases toxic fumes of nitrogen oxides.

Learn more about the Structure, physical and chemical properties of NO2 from the experts at BYJU’S.

Practise This Question

A tightly closed container contains 500 ml of gas. Now, the gas is carefully transported into a 1000 ml container without any leakage. What is the volume of gas in the new container?