Dinitrogen trioxide
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2008-06-09T03:17:07Z
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{{Chembox new
| Name = Dinitrogen trioxide
| ImageFile = Dinitrogen-trioxide-3D-vdW.png
| ImageSize = 200px
| ImageFile1 = Dinitrogen-trioxide-xtal-3D-vdW.png
| ImageName = Dinitrogen trioxide
| Section1 = {{Chembox Identifiers
| CASNo = 10544-73-7
}}
| Section2 = {{Chembox Properties
| Formula = N<sub>2</sub>O<sub>3</sub>
| MolarMass = 76.01
| Appearance = blue liquid
| Density = 1.4 × 10<sup>3</sup> kg m<sup>−3</sup>, liquid
| MeltingPt = −100.1°C (173.05 K)
| BoilingPt = 3°C (276 K)
}}<!--
{{Chembox/DeltaHf298|+91.20}}
{{Chembox/S298|314.63}}
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| Section7 = {{Chembox Hazards
| EUClass = Highly toxic ('''T+''')
| NFPA-H = 3
| NFPA-F =
| NFPA-R =
| NFPA-O = OX
| RPhrases = {{R26}}, {{R34}}
| SPhrases = {{S1/2}}, {{S9}}, {{S26}}, {{S28}},<br />{{S36/37/39}}, {{S45}}
}}
}}
'''Dinitrogen trioxide''' is the [[chemical compound]] with the [[chemical formula|formula]] N<sub>2</sub>O<sub>3</sub>. This deep blue [[liquid]] is one of binary [[nitrogen oxide]]s. It forms upon mixing equal parts of [[nitric oxide]] and [[nitrogen dioxide]] and cooling the mixture below −21°C (−6°F):
:NO + NO<sub>2</sub> <math>\overrightarrow{\leftarrow}</math> N<sub>2</sub>O<sub>3</sub>
Dinitrogen trioxide is only isolable at low temperatures, i.e. in the liquid and solid [[phase (matter)|phases]]. At higher temperatures the equilibrium favors the constituent gases. K<sub>diss</sub> = 193 kPa (25 °C).<ref>Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.</ref>
==Structure and bonding==
Dinitrogen trioxide has an unusually long N−N bond at 186 [[1 E-12 m|pm]]. Whereas N−N bonds are more often similar to that in [[hydrazine]] (145 pm), some other [[Nitrogen oxide|oxides of nitrogen]] do possess long N−N bonds, including [[dinitrogen tetroxide]] (175 pm). The N<sub>2</sub>O<sub>3</sub> molecule is planar and exhibits ''C<sub>s</sub>'' symmetry. The dimensions displayed below come from microwave spectroscopy of low-temperature, gaseous N<sub>2</sub>O<sub>3</sub>:
[[Image:Dinitrogen-trioxide-2D-geometry.png|400px|center|The bond lengths and angles of dinitrogen trioxide]]
It is the [[anhydride]] of the unstable [[nitrous acid]] (HNO<sub>2</sub>), and produces it when mixed into water. An alternative structure might be anticipated for the true anhydride, i.e. O=N-O-N=O, but this isomer is not observed. If the nitrous acid is not then used up quickly, it decomposes into [[nitric oxide]] and [[nitric acid]]. [[Nitrite]] [[salt]]s are sometimes produced by adding N<sub>2</sub>O<sub>3</sub> to solutions of bases:
:N<sub>2</sub>O<sub>3</sub> + 2 NaOH → 2 NaN<sub></sub>O<sub>2</sub> + H2O
Nitrogen Trioxide = NO3
==References==
<references/>
==External links==
*[http://www.npi.gov.au/database/substance-info/profiles/67.html National Pollutant Inventory - Oxides of nitrogen fact sheet]
* [http://www.webelements.com/webelements/compounds/text/N/N2O3-10544737.html Webelements: Compound data - dinitrogen trioxide]
* [http://www.c-f-c.com/supportdocs/nitrogen_oxi.htm Oxides of nitrogen - synthesis and uses]
* [http://www.chem.msu.su/rus/handbook/ivtan/79.html Ivtantermo - dinitrogen trioxide table of values]
[[Category:Oxides]]
[[Category:Nitrogen compounds]]
[[Category:Acidic oxides]]
[[cs:Oxid dusitý]]
[[da:Dinitrogentrioxid]]
[[de:Distickstofftrioxid]]
[[es:Óxido de nitrógeno (III)]]
[[ko:삼산화 이질소]]
[[ja:三酸化二窒素]]
[[pl:Tritlenek diazotu]]
[[ru:Оксид азота(III)]]
[[zh:三氧化二氮]]