nitrogen dioxide

Information about nitrogen dioxide



Nitrogen dioxide
Identifiers
CAS number10102-44-0
Properties
Molecular formulaNO2
Molar mass46.0055
Appearancebrown gas
Density1443 kg/m³, liquid
3.4 kg/m³, gas at 294.25 K
Melting point -11.2°C (261.95 K)
Boiling point 21.1°C (293.25 K)
Hazards
EU classificationHighly toxic (T+)
NFPA 704
0
3
0
 
R-phrasesR26, R34
S-phrasesS1/2, S9, S26, S28,S36/37/39, S45
Except where noted otherwise, data are given for
materials in their standard state
(at 25 C, 100 kPa)
Nitrogen dioxide is the chemical compound NO2. It is one of the several nitrogen oxides. This reddish-brown gas has a characteristic sharp, biting odor. NO2 is one of the most prominent air pollutants and a poison by inhalation.

Safety and pollution considerations

Nitrogen dioxide is toxic by inhalation. Symptoms of poisoning (lung edema) tend to appear several hours after one has inhaled a low but potentially fatal dose. Also, low concentrations (4 ppm) will anesthetize the nose, thus creating a potential for overexposure.

Long-term exposure to NO2 at concentrations above 40–100 µg/m³ causes adverse health effects [1]. The most important source of NO2 is internal combustion engines, which emit nitrogen oxides near people. A major industrial source is pulp mills.
Enlarge picture
NO2 pollution levels in Europe, from January 2003 to June 2004.


The map shown to the left, depicting results of satellite measurements, illustrates nitrogen dioxide as large scale pollutant, with rural background ground level concentrations in some areas around 30 µg/m³, not far below unhealthful levels. Nitrogen dioxide plays a role in atmospheric chemistry, including the formation of tropospheric ozone. A recent study by researchers at the University of California, San Diego, suggests a link between NO2 levels and Sudden Infant Death Syndrome [2].

See also

  • Nitryl
  • Nitrous oxide or N2O, "laughing gas", a linear molecule, isoelectronic with CO2 but with a nonsymmetric arrangement of atoms (NNO)
  • Nitric oxide or NO, a problematic pollutant, related to CO but with one additional electron.
  • NOx = all of the above in unspecified proportions but tending toward NO2.
More esoteric nitrogen oxides include N2O5 and the blue species N2O3.

Oxidized (cationic) and reduced (anionic) derivatives of many of these oxides exist: nitrite (NO2−), nitrate (NO3−), nitronium or NO2+, and nitrosonium or NO+. NO2 is intermediate between nitrite and nitronium:
:NO2+ + e− → NO2
:NO2 + e− → NO2−

References

External links

CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. They are also referred to as CAS numbers, CAS RNs or CAS #s.
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A chemical formula is a concise way of expressing information about the atoms that constitute a particular chemical compound. A chemical formula is also a short way of showing how a chemical reaction occurs.
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Molar mass, symbol M,[1] is the mass of one mole of a substance (chemical element or chemical compound).[2] It is a physical property which is characteristic of each pure substance.
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In physics, density is mass m per unit volume V—how heavy something is compared to its size. A small, heavy object, such as a rock or a lump of lead, is denser than a lighter object of the same size or a larger object of the same weight, such as pieces of
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The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. Although the phrase would suggest a specific temperature and is commonly and incorrectly used as such in most textbooks and literature, most crystalline compounds
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boiling point of a liquid is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid.[1][2][3][4]
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Council Directive 67/548/EEC of 27 June 1967 on the approximation of laws, regulations and administrative provisions relating to the classification, packaging and labelling of dangerous substances (as amended) is the main European Union law concerning chemical safety.
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NFPA 704 is a standard maintained by the U.S. National Fire Protection Association. It defines the colloquial "fire diamond" used by emergency personnel to quickly and easily identify the risks posed by nearby hazardous materials.
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R-phrases (short for Risk Phrases) are defined in Annex III of European Union Directive 67/548/EEC: Nature of special risks attributed to dangerous substances and preparations.
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S-phrases are defined in Annex IV of European Union Directive 67/548/EEC: Safety advice concerning dangerous substances and preparations. The list was consolidated and republished in Directive 2001/59/EC , where translations into other EU languages may be found.
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standard state of a material is its state at 1 bar (100 kilopascals exactly). This pressure was changed from 1 atm (101.325 kilopascals) by IUPAC in 1990.[1] The standard state of a material can be defined at any given temperature, most commonly 25 degrees Celsius,
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3, 5, 4, 2
(strongly acidic oxide)
Electronegativity 3.04 (Pauling scale)
Ionization energies
(more) 1st: 1402.3 kJmol−1
2nd: 2856 kJmol−1
3rd: 4578.1 kJmol−1

Atomic radius 65 pm
Atomic radius (calc.
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2, −1
(neutral oxide)
Electronegativity 3.44 (Pauling scale)
Ionization energies
(more) 1st: 1313.9 kJmol−1
2nd: 3388.3 kJmol−1
3rd: 5300.5 kJmol−1

Atomic radius 60 pm
Atomic radius (calc.
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Gas is one of the four major states of matter, consisting of freely moving atoms or molecules without a definite shape. Compared to the solid and liquid states of matter a gas has lower density and a lower viscosity.
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3, 5, 4, 2
(strongly acidic oxide)
Electronegativity 3.04 (Pauling scale)
Ionization energies
(more) 1st: 1402.3 kJmol−1
2nd: 2856 kJmol−1
3rd: 4578.1 kJmol−1

Atomic radius 65 pm
Atomic radius (calc.
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2, −1
(neutral oxide)
Electronegativity 3.44 (Pauling scale)
Ionization energies
(more) 1st: 1313.9 kJmol−1
2nd: 3388.3 kJmol−1
3rd: 5300.5 kJmol−1

Atomic radius 60 pm
Atomic radius (calc.
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Pulmonary edema
Classification & external resources

ICD-10 J 81.
ICD-9 514

DiseasesDB 11017
MedlinePlus 000140
eMedicine med/1955   radio/581 Pulmonary edema
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A pulp mill is a manufacturing facility that converts wood chips or other plant fiber source into a thick fiber board which can be shipped to a paper mill for further processing.
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Ozone (O3) is a key constituent of the troposphere (it is also an important constituent of certain regions of the stratosphere commonly known as the Ozone layer).
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University of California, San Diego (popularly known as UCSD, or sometimes UC San Diego) is a public, coeducational research university located in La Jolla, a seaside resort community of San Diego, California.
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MeSH D013398 Sudden infant death syndrome (SIDS) is a syndrome marked by the symptoms of sudden and unexplained death of an apparently healthy infant aged one month to one year.
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Nitryl is the nitrogen dioxide (NO2) moiety when it occurs in a larger compound. Examples include nitryl fluoride (NO2F) and nitryl chloride (NO2Cl).
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Nitrous oxide, dinitrogen oxide or dinitrogen monoxide, is a chemical compound with chemical formula N2O. Under room conditions, it is a colorless non-flammable gas, with a pleasant, slightly sweet odor and taste.
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isoelectronic[1] with each other if they have the same number of valence electrons and the same structure (number and connectivity of atoms), regardless of the nature of the elements involved.
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Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state.
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Nitric oxide or Nitrogen monoxide is a chemical compound with chemical formula NO. This gas is an important signaling molecule in the body of mammals including humans and is an extremely important intermediate in the chemical industry.
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Carbon monoxide, with the chemical formula CO, is a colorless, odorless, and tasteless gas. It is the product of the incomplete combustion of carbon-containing compounds, notably in internal-combustion engines.
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