Editing Nitrogen (section)

==Production==
Nitrogen gas is an [[industrial gas]] produced by the [[fractional distillation]] of [[liquid air]], or by mechanical means using gaseous air (pressurised reverse [[Osmotic pressure|osmosis membrane]] or [[pressure swing adsorption]]). Nitrogen gas generators using membranes or pressure swing adsorption (PSA) are typically more cost and energy efficient than bulk-delivered nitrogen.<ref>{{Cite web|url=http://www.parkern2.com/_literature_176619/A_Sustainable_Approach_to_the_Supply_of_Nitrogen|title=A Sustainable Approach to the Supply of Nitrogen|last=Froehlich|first=Peter|date=May 2013|website=www.parker.com|publisher=Parker Hannifin Corporation|access-date=24 November 2016|archive-date=16 March 2016|archive-url=https://web.archive.org/web/20160316190914/http://www.parkern2.com/_literature_176619/A_Sustainable_Approach_to_the_Supply_of_Nitrogen|url-status=live}}</ref> Commercial nitrogen is often a byproduct of air-processing for industrial concentration of [[oxygen]] for steelmaking and other purposes. When supplied compressed in cylinders it is often called OFN (oxygen-free nitrogen).<ref>{{Cite journal|doi= 10.1021/ie50569a032|title=Nitrogen Purfication. Pilot Plant Removal of Oxygen|year=1957|journal=Industrial & Engineering Chemistry|volume= 49|pages= 869–73|issue= 5|last1= Reich|first1= Murray|last2= Kapenekas|first2= Harry}}</ref> Commercial-grade nitrogen already contains at most 20&nbsp;ppm oxygen, and specially purified grades containing at most 2&nbsp;ppm oxygen and 10&nbsp;ppm [[argon]] are also available.<ref name="Greenwood409">Greenwood and Earnshaw, pp. 409–11</ref>

In a chemical laboratory, it is prepared by treating an aqueous solution of [[ammonium chloride]] with [[sodium nitrite]].<ref name="labProduction">{{Cite journal| last1 = Bartlett |first1 = J. K.| title = Analysis for nitrite by evolution of nitrogen: A general chemistry laboratory experiment | doi = 10.1021/ed044p475 | journal = Journal of Chemical Education | volume = 44 | issue = 8 | page = 475 | year = 1967 | bibcode = 1967JChEd..44..475B}}</ref>
:NH<sub>4</sub>Cl + NaNO<sub>2</sub> → N<sub>2</sub> + NaCl + 2 H<sub>2</sub>O

Small amounts of the impurities NO and HNO<sub>3</sub> are also formed in this reaction. The impurities can be removed by passing the gas through aqueous sulfuric acid containing [[potassium dichromate]].<ref name="labProduction" /> 

It can also be obtained by the thermal decomposition of [[ammonium dichromate]].<ref>{{cite journal | last1=Mahieu | first1=B. | last2=Apers | first2=D.J. | last3=Capron | first3=P.C. | title=Thermal decomposition of ammonium dichromate | journal=Journal of Inorganic and Nuclear Chemistry | publisher=Elsevier BV | volume=33 | issue=9 | year=1971 | issn=0022-1902 | doi=10.1016/0022-1902(71)80047-7 | pages=2857–2866}}</ref>
:3(NH<sub>4</sub>)<sub>2</sub>Cr<sub>2</sub>O<sub>7</sub> → 2N<sub>2</sub> + 9H<sub>2</sub>O + 3Cr<sub>2</sub>O<sub>3</sub> + 2NH<sub>3</sub> + 32O<sub>2</sub>
Very pure nitrogen can be prepared by the thermal decomposition of [[barium azide]] or [[sodium azide]].<ref>{{Cite journal | last1 = Eremets | first1 = M. I. | last2 = Popov | first2 = M. Y. | last3 = Trojan | first3 = I. A. | last4 = Denisov | first4 = V. N. | last5 = Boehler | first5 = R. | last6 = Hemley | first6 = R. J. | doi = 10.1063/1.1718250 | title = Polymerization of nitrogen in sodium azide | journal = The Journal of Chemical Physics | volume = 120 | issue = 22 | pages = 10618–23 | year = 2004 | pmid = 15268087|bibcode = 2004JChPh.12010618E }}</ref>
:2 NaN<sub>3</sub> → 2 Na + 3 N<sub>2</sub>