Sodium nitrate
200310
224311237
2008-07-08T08:03:17Z
220.233.166.202
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| ImageFileL1 = NaNitrate.png
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| IUPACName = Sodium nitrate
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| OtherNames = [[Caliche (mineral)|caliche]]; nitrate of soda; Chile saltpeter; saltpeter; soda niter; [[nitratine]]
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| CASNo = 7631-99-4
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| Formula = NaNO<sub>3</sub>
| MolarMass = 84.9947 g/mol
| Appearance = White powder or colorless crystals
| Density = 2.26 g/cm<sup>3</sup>, solid
| MeltingPt = 307 °C
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| BoilingPt = 653 °C
| Boiling_notes = decomposes
| Solubility = 87.4 g/100 mL water
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| DeltaHf = -468 kJ/mol
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| Entropy = 117 J/mol.K
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| NFPA-O = ox
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'''Sodium nitrate''' is the [[chemical compound]] with the [[chemical formula|formula]] NaNO<sub>3</sub>. This [[salts|salt]], also known as "Chile saltpeter" (to distinguish it from ordinary saltpeter, [[potassium nitrate]]), is a white solid which is very soluble in [[water]]. The mineral form is also known as '''[[nitratine]]''' or '''soda [[nitre]]'''.
Sodium nitrate is used as an ingredient in [[fertilizer]]s, pyrotechnics, and as [[rocket propellant|solid rocket propellant]]s, as well as in [[glass]] and [[pottery]] [[enamel]]s; the compound has been mined extensively for those purposes.
The mining of Chile saltpeter was such a profitable business that three nations, [[Chile]], [[Peru]], and [[Bolivia]] fought over the richest deposits in the [[War of the Pacific]]. The world's largest natural deposits of caliche ore were in the [[Atacama]] desert of [[Chile]], and many deposits were mined for over a century, until the 1940s, when its value declined dramatically in the first decades of the twentieth century (see [[Haber Process]]).
Chile still has the largest reserves of caliche, with active mines in such locations as Pedro de Valdivia, Maria Elena and Pampa Blanca. Sodium nitrate, [[potassium nitrate]], [[sodium sulfate]] and [[iodine]] are all obtained by the processing of caliche. The former Chilean saltpeter mining communities of [[Humberstone and Santa Laura Saltpeter Works|Humberstone and Santa Laura]] were declared Unesco World Heritage sites in 2005.
Sodium nitrate is also synthesized industrially by neutralizing [[Nitric Acid|nitric acid]] with [[Sodium carbonate|soda ash]].
==Applications==
Sodium nitrate was used extensively as a fertilizer and a raw material for the manufacture of gunpowder in the late nineteenth century.
Sodium nitrate has [[antimicrobial]] properties when used as a [[food preservative]]. It is found naturally in [[leafy green vegetable]]s.
Sodium nitrate should not be confused with the related compound, [[sodium nitrite]]. The presence of sodium nitrite in food is controversial due to the development of [[nitrosamine]]s when the food, primarily [[bacon]], is cooked at high temperatures. Its usage is carefully regulated in the production of cured products; in the United States, the concentration in finished products is limited to 200 ppm, and is usually lower. The nitrate compound itself is not harmful, however, and is among the antioxidants found in fresh vegetables. <ref>National Academy of Sciences - National Research Council Academy of Life Sciences. "The Health Effects of Nitrate, Nitrite and N-Nitroso Compounds". Washington DC: National Academy Press, 1981</ref>
It can be used in the production of [[nitric acid]] by combining it with [[sulfuric acid]] and subsequent separation through [[fractional distillation]] of the nitric acid, leaving behind a residue of [[sodium bisulfate]]. Hobbyist gold refiners use sodium nitrate to make a hybrid [[aqua regia]] that dissolves gold and other metals.
Less common applications include its use as a substitute oxidizer used in fireworks as a replacement for [[potassium nitrate]] commonly found in [[black powder]] and as a component in instant cold packs<ref>http://www.google.com/patents?id=HUcCAAAAEBAJ US patent 2,898,744</ref>.
Because sodium nitrate can be used as a [[Phase Change Material]] it may be used for [[heat transfer]] in [[solar power]] plants.<ref>http://www.google.com/patents?id=4ygUAAAAEBAJ US patent 6,877,508</ref>
==Notes and references==
{{Reflist}}
==Further reading==
* Dennis W. Barnum. (2003). "Some History of Nitrates." ''Journal of Chemical Education.'' v. 80, p. 1393-. [http://jchemed.chem.wisc.edu/Journal/Issues/2003/Dec/abs1393.html link].
==External links==
* [http://www.atsdr.cdc.gov/csem/nitrate/ ATSDR - Case Studies in Environmental Medicine - Nitrate/Nitrite Toxicity] U.S. [[Department of Health and Human Services]] (public domain)
* [http://www.inchem.org/documents/jecfa/jecmono/v38aje06.htm FAO/WHO report]
[[Category:Nitrates]]
[[Category:Sodium compounds]]
[[Category:Salts]]
[[Category:Preservatives]]
[[Category:Pyrotechnic oxidizers]]
[[Category:Sodium minerals]]
[[Category:Nitrate minerals]]
[[Category:Deliquescent substances]]
[[ar:نترات صوديوم]]
[[bs:Natrijum nitrat]]
[[cs:Dusičnan sodný]]
[[de:Natriumnitrat]]
[[es:Nitrato de sodio]]
[[fr:Nitrate de sodium]]
[[id:Natrium nitrat]]
[[it:Nitrato di sodio]]
[[he:נתרן חנקתי]]
[[lv:Nātrija nitrāts]]
[[hu:Nátrium-nitrát]]
[[nl:Natriumnitraat]]
[[ja:硝酸ナトリウム]]
[[no:Natriumnitrat]]
[[pl:Azotan(V) sodu]]
[[pt:Nitrato de sódio]]
[[qu:Natriyu qullpa]]
[[sv:Chilesalpeter]]
[[uk:Натрієва селітра]]
[[zh:硝酸鈉]]