Nitrogen dioxide


Nitrogen dioxide is a reddish-brown gas and in high concentrations it is partially associated to N2 O4.

Below its boiling point, it is a colourless liquid. This compound is formed by the action of nitric acid on reducing agents, by the combustion of nitrogenous organic material and the oxidation, in air or oxygen, of nitric oxide (q.v.).

High concentrations are frequently present in silos where ensilage is stored; varying amounts result from the detonation of nitro or nitrate explosives. Its physiochemical properties include:

Molecular weight : 46.01
Specific gravity : 1.448 at 20 deg. C
Melting point : -9.3 deg. C
Boiling Point : 21.15 deg. C
Condensation point : 21 deg C
Vapour pressure : 720 torr at 20 deg. C
Vapour density : 1.58 (air = 1)


It is soluble in concentrated nitric and sulfuric acids.