Nitrogen dioxide 238528 225580808 2008-07-14T12:11:22Z ToePeu.bot 4082686 robot Modifying: [[ar:ثنائي أكسيد نيتروجين]] {{Chembox new | Name = Nitrogen dioxide | ImageFile = Nitrogen-dioxide-2D-dimensions.png | ImageSize = 150px | ImageName = Nitrogen dioxide | ImageFile1 = Nitrogen-dioxide-3D-vdW.png | ImageSize1 = 150px | ImageName1 = Nitrogen dioxide | ImageFile2 = NO2-Schema-Lewis.png | ImageSize2 = 250px | ImageName2 = Nitrogen dioxide Resonance | ImageFile3 = Diossido di azoto.jpg | ImageSize3 = 150px | ImageName3 = left|thumb|Nitrogen dioxide in a test tube | Section1 = {{Chembox Identifiers | CASNo = 10102-44-0 }} | Section2 = {{Chembox Properties | Formula = NO<sub>2</sub> | MolarMass = 46.0055 | Appearance = brown gas | Density = 1443 kg/m³, liquid<br /> 3.4 kg/m³, gas at 294.25 K | MeltingPt = -11.2°C (261.95 K) | BoilingPt = 21.1°C (293.25 K) }} | Section7 = {{Chembox Hazards | EUClass = Highly toxic ('''T+''') | NFPA-H = 3 | Flammability=0 | NFPA-F = | NFPA-R = 0 | Other=OX | RPhrases = {{R26}}, {{R34}} | SPhrases = {{S1/2}}, {{S9}}, {{S26}}, {{S28}},{{S36/37/39}}, {{S45}} }} }} '''Nitrogen dioxide''' is the [[chemical compound]] [[Nitrogen|N]][[Oxygen|O]]<sub>2</sub>. It is one of the several [[nitrogen oxide]]s. This reddish-brown [[gas]] has a characteristic sharp, biting odor. [[Nitrogen|N]][[Oxygen|O]]<sub>2</sub> is one of the most prominent air pollutants and a poison by inhalation. ==Preparation== Nitrogen dioxide (NO<sub>2</sub>) is prepared by simple reaction of [[nitric acid]] (HNO<sub>3</sub>) over [[copper]] metal. The reaction is the following: :4HNO<sub>3</sub>(aq) + Cu(s) → Cu(NO<sub>3</sub>)<sub>2</sub>(aq) + 2NO<sub>2</sub>(g) + 2H<sub>2</sub>O(L) ==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 NO<sub>2</sub> at concentrations above 40&ndash;100 µg/m³ causes adverse health effects<ref>{{cite web|url=http://www.euro.who.int/document/e79097.pdf|title=Health Aspects of Air Pollution with Particulate Matter,Ozone and Nitrogen Dioxide|accessdate=2008-02-25}}</ref>. Nitrogen dioxide is formed in most [[combustion]] processes using [[air]] as the [[oxidant]]. At elevated temperatures [[nitrogen]] combines with [[oxygen]] to form nitrogen dioxide: : 2O<sub>2</sub> + N<sub>2</sub> → 2 NO<sub>2</sub> The most important sources of NO<sub>2</sub> are [[internal combustion engines]] <ref>{{cite journal|last=Son |first=Busoon |authorlink= |coauthors= Wonho Yang, Patrick Breysse, Taewoong Chung and Youngshin Lee|year=2004 |month=March|title=Estimation of occupational and nonoccupational nitrogen dioxide exposure for Korean taxi drivers using a microenvironmental model |journal=Environmental Research |volume=94 |issue=3 |pages=291–296 |id= |url= http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WDS-49WMV2W-1&_user=432163&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000020718&_version=1&_urlVersion=0&_userid=432163&md5=1568528cb723b88921f97d88ebddd336|accessdate= 2008-02-25 |quote=|doi=10.1016/j.envres.2003.08.004}}</ref>, [[thermal power station]]s and, to a lesser extent, [[pulp mill]]s.<ref>{{cite web|url=http://www.metsabotnia.com/en/default.asp?path=204,215,268,267 |title= Air emissions|publisher=Botnia|accessdate=2008-02-25}}</ref> The excess air required for complete combustion of fuels in these processes introduces nitrogen into the combustion reactions at high temperatures and produces nitrous oxides ([[NOx]]). Limiting NOx production demands the precise control of the amount of air used in combustion. The map shown below, depicting results of satellite measurements over Europe, 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 NO<sub>2</sub> levels and [[Sudden Infant Death Syndrome]]. <ref>{{cite web|url=http://www.medicineonline.com/news/12/1110/Sids-Linked-to-Nitrogen-Dioxide-Pollution.html|title=Sids Linked to Nitrogen Dioxide Pollution|accessdate=2008-02-25}}</ref> [[Image:NO2 pollution europe hires.jpg|none|thumb|300px|NO<sub>2</sub> pollution levels in [[Europe]], from January 2003 to June 2004.]] ==See also== [[Image:N02-N2O4.jpg|200px|thumb|right|thumb|Nitrogen dioxide (NO<sub>2</sub>) gas converts to the colorless gas [[dinitrogen tetroxide]] (N<sub>2</sub>O<sub>4</sub>) at low temperatures, and converts back to NO<sub>2</sub> at higher temperatures. Both bottles in this photograph contain equal amounts of gas at different temperatures.]] *[[Nitryl]] *[[Nitrous oxide]] or N<sub>2</sub>O, "laughing gas", a linear molecule, [[isoelectronic]] with [[carbon dioxide|CO<sub>2</sub>]] but with a nonsymmetric arrangement of atoms (NNO) *[[Nitric oxide]] or NO, a problematic pollutant that is short lived because it converts to NO2 in the presence of free [[oxygen]]. *[[Nitrogen oxide|NO<sub>x</sub>]] = all of the above in unspecified proportions but tending toward NO<sub>2</sub>. More esoteric nitrogen oxides include [[dinitrogen pentoxide|N<sub>2</sub>O<sub>5</sub>]] and the blue species [[dinitrogen trioxide|N<sub>2</sub>O<sub>3</sub>]]. Oxidized (cationic) and reduced (anionic) derivatives of many of these oxides exist: [[nitrite]] (NO<sub>2</sub><sup>−</sup>), [[nitrate]] (NO<sub>3</sub><sup>−</sup>), [[nitronium]] or NO<sub>2</sub><sup>+</sup>, and [[nitrosonium]] or NO<sup>+</sup>. NO<sub>2</sub> is intermediate between nitrite and nitronium: ::NO<sub>2</sub><sup>+</sup> + e<sup>−</sup> → NO<sub>2</sub> ::NO<sub>2</sub> + e<sup>−</sup> → NO<sub>2</sub><sup>−</sup> <!--In this two step process, the O-N-O angle changes from 180° to 134° to 115°--> * [[Birkeland-Eyde process]] ==References== <references/> ==External links== *[http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc09/icsc0930.htm International Chemical Safety Card 0930] *[http://www.npi.gov.au/database/substance-info/profiles/67.html National Pollutant Inventory - Oxides of nitrogen fact sheet] *[http://www.cdc.gov/niosh/npg/npgd0454.html NIOSH Pocket Guide to Chemical Hazards] *WHO-Europe reports: [http://www.euro.who.int/document/e79097.pdf Health Aspects of Air Pollution (2003)] (PDF) and "[http://www.euro.who.int/document/E82790.pdf Answer to follow-up questions from CAFE (2004)] (PDF) *[http://www.greenfacts.org/air-pollution/nitrogen-dioxide-no2/index.htm Nitrogen Dioxide Air Pollution] *[http://esamultimedia.esa.int/images/EarthObservation/pollution_global_hires.jpg Nitrogen dioxide pollution in the world (image)] *[http://www.compchemwiki.org/index.php?title=Nitrogen_dioxide Computational Chemistry Wiki] [[Category:Nitrogen compounds]] [[Category:Oxides]] [[Category:Bleaches]] [[Category:Hazardous air pollutants]] [[Category:Smog]] [[ar:ثنائي أكسيد نيتروجين]] [[bs:Dušik dioksid]] [[ca:Diòxid de nitrogen]] [[cs:Oxid dusičitý]] [[da:Nitrogendioxid]] [[de:Stickstoffdioxid]] [[es:Óxido de nitrógeno (IV)]] [[fr:Dioxyde d'azote]] [[ko:이산화 질소]] [[it:Diossido di azoto]] [[nl:Stikstofdioxide]] [[ja:二酸化窒素]] [[no:Nitrogendioksid]] [[pl:Tlenek azotu(IV)]] [[pt:Dióxido de azoto]] [[ru:Оксид азота(IV)]] [[sk:Oxid dusičitý]] [[sl:Dušikov dioksid]] [[fi:Typpidioksidi]] [[sv:Kvävedioxid]] [[uk:Діоксид азоту]] [[zh:二氧化氮]]