Editing Nitrogen (section)

===Liquid===
As a [[cryogenic]] liquid, liquid nitrogen can be dangerous by causing [[cold burn]]s on contact, although the [[Leidenfrost effect]] provides protection for very short exposure (about one second).<ref>{{cite journal|last1=Walker|first1=Jearl|title=Boiling and the Leidenfrost Effect|journal=Fundamentals of Physics|pages=1–4|url=http://www.wiley.com/college/phy/halliday320005/pdf/leidenfrost_essay.pdf|access-date=11 October 2014|archive-date=13 December 2019|archive-url=https://web.archive.org/web/20191213010916/https://www.wiley.com/college/phy/halliday320005/pdf/leidenfrost_essay.pdf|url-status=live}}</ref> Ingestion of liquid nitrogen can cause severe internal damage. For example, in 2012, a young woman in England had to have her stomach removed after ingesting a cocktail made with liquid nitrogen.<ref>{{cite web|url=https://www.bbc.co.uk/news/uk-19878511 |title=Liquid nitrogen cocktail leaves teen in hospital|date=2012-10-08|publisher=BBC News|archiveurl=https://web.archive.org/web/20170412232656/http://www.bbc.co.uk/news/uk-19878511|archivedate=2017-04-12 }}</ref>

Because the liquid-to-gas [[expansion ratio]] of nitrogen is 1:694 at 20&nbsp;°C, a tremendous amount of force can be generated if liquid nitrogen is rapidly vaporised in an enclosed space. In an incident on January 12, 2006, at [[Texas A&M University]], the pressure-relief devices of a tank of liquid nitrogen were malfunctioning and later sealed. As a result of the subsequent pressure buildup, the tank failed catastrophically. The force of the explosion was sufficient to propel the tank through the ceiling immediately above it, shatter a reinforced concrete beam immediately below it, and blow the walls of the laboratory 0.1–0.2&nbsp;m off their foundations.<ref>{{cite web |title=Investigative Report on Chemistry 301A Cylinder Explosion |author=Mattox, Brent S. |publisher=Texas A&M University |format=reprint |url=http://ucih.ucdavis.edu/docs/chemistry_301a.pdf |url-status=dead |archive-url=https://web.archive.org/web/20140430205659/http://ucih.ucdavis.edu/docs/chemistry_301a.pdf |archive-date=2014-04-30 }}</ref>

Liquid nitrogen readily evaporates to form gaseous nitrogen, and hence the precautions associated with gaseous nitrogen also apply to liquid nitrogen.<ref name="BCGACOPCP30">British Compressed Gases Association (2000) BCGA Code of Practice CP30. {{cite web|url=http://www.bcga.co.uk/preview/products.php?g1=3ff921&n=2 |title=The Safe Use of Liquid nitrogen Dewars up to 50 litres.|archive-url=https://web.archive.org/web/20070718050900/http://www.bcga.co.uk/preview/products.php?g1=3ff921&n=2 |archive-date=2007-07-18 |issn=0260-4809}}.</ref><ref>{{cite web|url=http://www.csb.gov/assets/1/19/Valero_Case_Study.pdf |title=Confined Space Entry – Worker and Would-be Rescuer Asphyxiated|archive-url=https://web.archive.org/web/20150922022123/http://www.csb.gov/assets/1/19/Valero_Case_Study.pdf |archive-date=2015-09-22 |publisher= Valero Refinery Asphyxiation Incident Case Study.}}</ref><ref>{{cite web|url=http://news.bbc.co.uk/2/hi/uk_news/scotland/484813.stm |title=Inquiry after man dies in chemical leak|archive-url=https://web.archive.org/web/20170107063950/http://news.bbc.co.uk/2/hi/uk_news/scotland/484813.stm |archive-date=2017-01-07|publisher=BBC News|date=1999-10-25}}</ref> For example, [[oxygen sensor]]s are sometimes used as a safety precaution when working with liquid nitrogen to alert workers of gas spills into a confined space.<ref name="usn">{{Cite book |title=Liquid Nitrogen – Code of practice for handling |year=2007 |publisher=Birkbeck, University of London |location=United Kingdom |url=http://www.bbk.ac.uk/so/policies/liqn2 |access-date=2012-02-08 |archive-date=2018-06-12 |archive-url=https://web.archive.org/web/20180612141434/http://www.bbk.ac.uk/so/policies/liqn2 |url-status=live }}</ref>

Vessels containing liquid nitrogen can [[liquid oxygen|condense oxygen]] from air. The liquid in such a vessel becomes increasingly enriched in oxygen (boiling point −183&nbsp;°C, higher than that of nitrogen) as the nitrogen evaporates, and can cause violent oxidation of organic material.<ref>{{Cite web|title = Liquid Nitrogen Safety|author = Levey, Christopher G.|publisher = Thayer School of Engineering at Dartmouth|url = http://engineering.dartmouth.edu/microeng/ln2.html|access-date = 2016-11-23|archive-date = 2016-03-05|archive-url = https://web.archive.org/web/20160305020126/http://engineering.dartmouth.edu/microeng/ln2.html|url-status = live}}</ref>