Oxides of Nitrogen: Overview
Description
Oxides of nitrogen are a mixture of gases that are composed of nitrogen and oxygen. Two of the most toxicologically significant compounds are nitric oxide (NO) and nitrogen dioxide (NO2). Other gases belonging to this group are nitrogen monoxide (or nitrous oxide, N2O), and nitrogen pentoxide (NO5).
Nitrogen dioxide is produced for the manufacture of nitric acid. Most nitric acid is used in the manufacture of fertilisers, while some is used in the production of explosives for both military and mining uses.
Substance details
Substance name: Oxides of nitrogen
CASR number: N/A
Molecular formula: NO, NO2, N2O and N2O5
Synonyms: NO: nitric oxide, nitrogen oxide, nitrogen monoxide, mononitrogen monoxide
NO2: nitrogen dioxide
Physical properties
NO: sharp, sweet-smelling, colourless gas
Melting point: -163.6°C
Boiling point: -151.8°C
Relative Density: 1.04 (air = 1)
NO2: reddish-brown gas with irritating odour.
Melting point: -9.3°C
Boiling point: 21.15°C
Vapour Density: 1.58
Chemical properties
NO only burns when heated with hydrogen, and forms nitric acid (a strong acid) when dissolved in water.
NO2 is sparingly soluble in water to form nitrous acid (a weak acid).
Further information
The National Pollutant Inventory (NPI) holds data for all sources of Oxides of Nitrogen emissions in Australia.
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