Sodium nitrate

{{Short description|Chemical compound}} {{Distinguish|sodium nitrite|sodium nitride|nitratine}} {{chembox |ImageFile = Dusičnan sodný.JPG |Verifiedfields = changed |Watchedfields = changed |verifiedrevid = 441025959 |ImageFileL1 = Sodium nitrate.svg |ImageClassL1 = skin-invert-image |ImageFileR1 = Sodium-nitrate-unit-cell-3D-balls.png |ImageClassR1 = bg-transparent |IUPACName = Sodium nitrate |OtherNames = Peru saltpeter<br/>Soda niter<br/>cubic niter |Section1={{Chembox Identifiers |ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |ChemSpiderID = 22688 |UNII_Ref = {{fdacite|correct|FDA}} |UNII = 8M4L3H2ZVZ |InChI = 1/NO3.Na/c2-1(3)4;/q-1;+1 |InChIKey = VWDWKYIASSYTQR-UHFFFAOYAL |SMILES = [Na+].[O-][N+]([O-])=O |StdInChI_Ref = {{stdinchicite|correct|chemspider}} |StdInChI = 1S/NO3.Na/c2-1(3)4;/q-1;+1 |StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} |StdInChIKey = VWDWKYIASSYTQR-UHFFFAOYSA-N |CASNo = 7631-99-4 |ChEMBL_Ref = {{ebicite|changed|EBI}} |ChEMBL = 1644698 |CASNo_Ref = {{cascite|correct|CAS}} |EINECS = 231-554-3 |UNNumber = 1498 |PubChem = 24268 |RTECS = WC5600000 }} |Section2={{Chembox Properties |Formula = NaNO₃ |MolarMass = 84.9947 g/mol |Appearance = White powder or colorless crystals |Odor = sweet |Density = 2.257 g/cm³, solid |MeltingPtC = 308 |BoilingPtC = 380 |BoilingPt_notes = decomposes |Solubility = 73 g/100 g water (0&nbsp;°C) <br /> 91.2 g/100 g water (25&nbsp;°C)<ref name="Haynes2016">{{cite book|last=Haynes|first=William M.|title=CRC Handbook of Chemistry and Physics|url=https://books.google.com/books?id=VVezDAAAQBAJ|date=2016-06-22|publisher=CRC Press|isbn=978-1-4987-5429-3}}</ref><ref name="pubchem">{{cite web |title=Sodium nitrate |work=PubChem |date= |access-date=11 June 2021 |url= https://pubchem.ncbi.nlm.nih.gov/compound/Sodium-nitrate#section=Solubility}}</ref><br /> 180 g/100 g water (100&nbsp;°C) |SolubleOther = very soluble in ammonia, hydrazine <br /> soluble in alcohol<br /> slightly soluble in pyridine <br /> insoluble in acetone |RefractIndex = 1.587 (trigonal) <br /> 1.336 (rhombohedral) |Viscosity = 2.85 cP (317&nbsp;°C) |MagSus = &minus;25.6·10⁻⁶ cm³/mol }} |Section3={{Chembox Structure |CrystalStruct = trigonal and rhombohedral }} |Section4={{Chembox Thermochemistry |DeltaHf = −467&nbsp;kJ/mol<ref name=b1>{{cite book| author = Zumdahl, Steven S.|title =Chemical Principles 6th Ed| publisher = Houghton Mifflin Company| year = 2009| isbn = 978-0-618-94690-7|page=A23}}</ref> |DeltaGf = −365.9 kJ/mol |Entropy = 116&nbsp;J/(mol K)<ref name=b1/> |HeatCapacity = 93.05 J/(mol K) }} |Section5={{Chembox Hazards |ExternalSDS = [http://www.inchem.org/documents/icsc/icsc/eics0185.htm ICSC 0185] |MainHazards = Harmful ('''Xn''')<br />Oxidant ('''O''') |GHSPictograms = {{GHS07}}{{GHS03}} |NFPA-H = 1 |NFPA-F = 0 |NFPA-R = 0 |NFPA-S = OX |FlashPt = Non-flammable |LD50 = 3236 mg/kg }} |Section6={{Chembox Related |OtherAnions = Sodium nitrite |OtherCations = Lithium nitrate<br/>Potassium nitrate<br/>Rubidium nitrate<br/>Caesium nitrate |OtherCompounds = Sodium sulfate<br/>Sodium chloride }} }}

'''Sodium nitrate''' is the chemical compound with the formula NaNO₃. This alkali metal nitrate salt is also known as '''Chile saltpeter''' (large deposits of which were historically mined in Chile)<ref name=nitrate_towns>{{cite web |title=The Nitrate Towns of Chile |url=https://www.atlasobscura.com/places/nitrate-towns-chile |website=Atlas Obscura |access-date=27 May 2019 |language=en}}</ref><ref name=ghost_towns>{{cite news |last1=Mutic |first1=Anja |title=The ghost towns of northern Chile |url=https://www.washingtonpost.com/lifestyle/travel/the-ghost-towns-of-northern-chile/2012/10/25/fa4adad0-16e2-11e2-a55c-39408fbe6a4b_story.html |access-date=27 May 2019 |newspaper=Washington Post |date=26 October 2012 |language=en}}</ref> to distinguish it from ordinary saltpeter, potassium nitrate. The mineral form is also known as nitratine, nitratite or soda niter.

Sodium nitrate is a white deliquescent solid very soluble in water. It is a readily available source of the nitrate anion (NO₃⁻), which is useful in several reactions carried out on industrial scales for the production of fertilizers, pyrotechnics, smoke bombs and other explosives, glass and pottery enamels, food preservatives (esp. meats), and solid rocket propellant. It has been mined extensively for these purposes.

==History== The first shipment of saltpeter to Europe arrived in England from Peru in 1820 or 1825, right after that country's independence from Spain, but did not find any buyers and was dumped at sea in order to avoid customs toll.<ref>S. H. Baekeland "Några sidor af den kemiska industrien" (1914) ''Svensk Kemisk Tidskrift'', [https://runeberg.org/svkemtid/1914/0144.html p. 140].</ref><ref name="uppfinn">Friedrich Georg Wieck, ''Uppfinningarnas bok'' (1873, Swedish translation of ''Buch der Erfindungen''), [https://rruneberg.org/uppfinn/4/0485.html vol. 4, p. 473].</ref> With time, however, the mining of South American saltpeter became a profitable business (in 1859, England alone consumed 47,000 metric tons).<ref name="uppfinn"/> Chile fought the War of the Pacific (1879–1884) against the allies Peru and Bolivia and took over their richest deposits of saltpeter. In 1919, Ralph Walter Graystone Wyckoff determined its crystal structure using X-ray crystallography.

{{Anchor|Sources}}

==Occurrence== alt=Advertisement for the product|thumb|left|Advertisement for sodium nitrate fertilizer from Chile on a wall of a village in the Algarve area of Portugal thumb|left|Mines of Chile, green is sodium nitrate area The largest accumulations of naturally occurring sodium nitrate are found in Chile and Peru, where nitrate salts are bound within mineral deposits called caliche ore.<ref>Stephen R. Bown, ''A Most Damnable Invention: Dynamite, Nitrates, and the Making of the Modern World'', Macmillan, 2005, {{ISBN|0-312-32913-X}}, p. 157.</ref> Nitrates accumulate on land through marine-fog precipitation and sea-spray oxidation/desiccation followed by gravitational settling of airborne NaNO₃, KNO₃, NaCl, Na₂SO₄, and I, in the hot-dry desert atmosphere.<ref>{{cite conference|url=https://gsa.confex.com/gsa/inqu/finalprogram/abstract_55601.htm|title=On the Origin of Saltpeter, Northern Chile Coast|author1=Arias, Jaime|date=24 Jul 2003|publisher=International Union for Quaternary Research|access-date=19 Aug 2018|archive-url=https://web.archive.org/web/20160304100458/https://gsa.confex.com/gsa/inqu/finalprogram/abstract_55601.htm|archive-date=4 March 2016}}</ref> El Niño/La Niña extreme aridity/torrential rain cycles favor nitrates accumulation through both aridity and water solution/remobilization/transportation onto slopes and into basins; capillary solution movement forms layers of nitrates; pure nitrate forms rare veins. For more than a century, the world supply of the compound was mined almost exclusively from the Atacama desert in northern Chile until, at the turn of the 20th century, German chemists Fritz Haber and Carl Bosch developed a process for producing ammonia from the atmosphere on an industrial scale (see Haber process). With the onset of World War I, Germany began converting ammonia from this process into a synthetic ''Chilean saltpeter'', which was as practical as the natural compound in production of gunpowder and other munitions. By the 1940s, this conversion process resulted in a dramatic decline in demand for sodium nitrate procured from natural sources.

Chile still has the largest reserves of caliche, with active mines in such locations as Valdivia, María Elena and Pampa Blanca, and there it used to be called ''white gold''.<ref name=nitrate_towns/><ref name=ghost_towns/> 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 were declared UNESCO World Heritage sites in 2005.

== Synthesis == Sodium nitrate is also synthesized industrially by neutralizing nitric acid with sodium carbonate or sodium bicarbonate:

:2 HNO₃ + Na₂CO₃ → 2 NaNO₃ + H₂O + CO₂

:HNO₃ + NaHCO₃ → NaNO₃ + H₂O + CO₂

or also by neutralizing it with sodium hydroxide (however, this reaction is very exothermic):

:HNO₃ + NaOH → NaNO₃ + H₂O

or by mixing stoichiometric amounts of ammonium nitrate and sodium hydroxide, sodium bicarbonate or sodium carbonate:

:NH₄NO₃ + NaOH → NaNO₃ + NH₄OH

:NH₄NO₃ + NaHCO₃ → NaNO₃ + NH₄HCO₃

:2NH₄NO₃ + Na₂CO₃ → 2NaNO₃ + (NH₄)₂CO₃

==Uses== Most sodium nitrate is used in fertilizers, where it supplies a water-soluble form of nitrogen. Its use, which is mainly outside of high-income countries, is attractive since it does not alter the pH of the soil. Another major use is as a complement to ammonium nitrate in explosives. Molten sodium nitrate and its solutions with potassium nitrate have good thermal stability (up to 600&nbsp;°C) and high heat capacities. These properties are suitable for thermally annealing metals and for storing thermal energy in solar applications.<ref name=Ullmann>{{Ullmann|doi=10.1002/14356007.a17_265|title=Nitrates and Nitrites|year=2000|last1=Laue|first1=Wolfgang|last2=Thiemann|first2=Michael|last3=Scheibler|first3=Erich|last4=Wiegand|first4=Karl}}</ref>

=== Food === Sodium nitrate is also a food additive used as a preservative and color fixative in cured meats and poultry; it is listed under its INS number 251 or E number E251. It is approved for use in the EU,<ref>UK Food Standards Agency: {{cite web|url=http://www.food.gov.uk/safereating/chemsafe/additivesbranch/enumberlist|title=Current EU approved additives and their E Numbers|access-date=2011-10-27}}</ref> US<ref>US Food and Drug Administration: {{cite web|url=https://www.fda.gov/Food/FoodIngredientsPackaging/FoodAdditives/ucm191033.htm#ftnT|archive-url=https://web.archive.org/web/20100108135705/http://www.fda.gov/Food/FoodIngredientsPackaging/FoodAdditives/ucm191033.htm#ftnT|url-status=dead|archive-date=January 8, 2010|title=Listing of Food Additives Status Part II|website=Food and Drug Administration |access-date=2011-10-27}}</ref> and Australia and New Zealand.<ref>Australia New Zealand Food Standards Code{{cite web|url=http://www.comlaw.gov.au/Details/F2011C00827|title=Standard 1.2.4 – Labelling of ingredients|date=8 September 2011 |access-date=2011-10-27}}</ref> Sodium nitrate should not be confused with sodium nitrite, which is also a common food additive and preservative used, for example, in deli meats.

=== Thermal storage === Sodium nitrate has also been investigated as a phase-change material for thermal energy recovery, owing to its relatively high melting enthalpy of 178 J/g.<ref name=":0">{{cite journal|last1=Bauer|first1=Thomas|last2=Laing|first2=Doerte|last3=Tamme|first3=Rainer|date=2011-11-15|title=Characterization of Sodium Nitrate as Phase Change Material|journal=International Journal of Thermophysics|volume=33|issue=1|pages=91–104|doi=10.1007/s10765-011-1113-9|s2cid=54513228|issn=0195-928X}}</ref><ref>{{cite journal|date=1999-06-14|title=Reference materials for calorimetry and differential thermal analysis|url=https://www.sciencedirect.com/science/article/abs/pii/S004060319900009X|journal=Thermochimica Acta|language=en|volume=331|issue=2|pages=93–204|doi=10.1016/S0040-6031(99)00009-X|issn=0040-6031|author=ICTAC Working Group|last2=Sabbah |first2=R. |last3=Xu-Wu |first3=An|last4=Chickos|first4=J.S.|last5=Leitão |first5=M.L.Planas|last6=Roux |first6=M.V.|last7=Torres |first7=L.A.|bibcode=1999TcAc..331...93S |display-authors=2|url-access=subscription}}</ref> Examples of the applications of sodium nitrate used for thermal energy storage include solar thermal power technologies and direct steam generating parabolic troughs.<ref name=":0" />

=== Steel coating === {{Main article|Black oxide}} Sodium nitrate is used in a steel coating process in which it forms a surface of magnetite layer.<ref>{{cite book |last=Fauzi |first=Ahmad Asyraf Bin Ahmad |url=https://books.google.com/books?id=ImcFywEACAAJ |title=Production of Magnetite Thin Film Over Steel Substrate Using Hot Alkaline Nitrate Blackening Method |date=2014 |publisher=Universitat Politècnica de Catalunya. Escola Politècnica Superior d'Enginyeria de Vilanova i la Geltrú. Departament de Ciència dels Materials i Enginyeria Metal·lúrgica, 2014 (Grau en Enginyeria Mecànica) |language=en}}</ref>

==Health concerns== Studies have shown a link between increased levels of nitrates and increased deaths from certain diseases including Alzheimer's disease, diabetes mellitus, stomach cancer, and Parkinson's disease: possibly through the damaging effect of nitrosamines on DNA; however, little has been done to control for other possible causes in the epidemiological results.<ref>{{cite journal |pmid=19363256 |year=2009 |last1=De La Monte |first1=SM |last2=Neusner |first2=A |last3=Chu |first3=J |last4=Lawton |first4=M |title=Epidemilogical trends strongly suggest exposures as etiologic agents in the pathogenesis of sporadic Alzheimer's disease, diabetes mellitus, and non-alcoholic steatohepatitis |volume=17 |issue=3 |pages=519–29 |doi=10.3233/JAD-2009-1070 |journal=Journal of Alzheimer's Disease |pmc=4551511}}</ref> Nitrosamines, formed in cured meats containing sodium nitrate and nitrite, have been linked to gastric cancer and esophageal cancer.<ref>{{cite journal |title=Nitrosamine and related food intake and gastric and oesophageal cancer risk: a systematic review of the epidemiological evidence |author1=Jakszyn, Paula |author2=Gonzalez, Carlos-Alberto |journal=World Journal of Gastroenterology |volume=12 |issue=27 |pages=4296–4303 |date=21 Jul 2006 |pmc=4087738 |pmid=16865769 |doi=10.3748/wjg.v12.i27.4296 |doi-access=free}}</ref> Sodium nitrate and nitrite are associated with a higher risk of colorectal cancer.<ref>{{cite journal |pmid=20215514 |year=2010 |last1=Cross |first1=AJ|author1-link=Amanda Cross (scientist) |last2=Ferrucci |first2=LM |last3=Risch |first3=A |last4=Graubard |first4=BI |last5=Ward |first5=MH |last6=Park |first6=Y |last7=Hollenbeck |first7=AR |last8=Schatzkin |first8=A |last9=Sinha |first9=R |display-authors=3 |title=A large prospective study of meat consumption and colorectal cancer risk: An investigation of potential mechanisms underlying this association |volume=70 |issue=6 |pages=2406–14 |doi=10.1158/0008-5472.CAN-09-3929 |pmc=2840051 |journal=Cancer Research}}</ref>

Nitrates are key intermediates and effectors in the primary vasculature signaling which is necessary for all mammals to survive.<ref>{{cite journal |last1=Machha |first1=Ajay |last2=Schechter |first2=Alan N. |date=August 2011 |title=Dietary nitrite and nitrate: a review of potential mechanisms of cardiovascular benefits |journal=European Journal of Nutrition |volume=50 |issue=5 |pages=293–303 |doi=10.1007/s00394-011-0192-5 |issn=1436-6207 |pmc=3489477 |pmid=21626413}}</ref>

==See also==

* Sodium nitrite

==References== {{Reflist}}

==Further reading== * {{cite journal|last1=Archer|first1=Donald G.|title=Thermodynamic properties of the NaNO₃ + H₂O system|journal=Journal of Physical and Chemical Reference Data|volume=29|issue=5|year=2000|pages=1141–1156|issn=0047-2689|doi=10.1063/1.1329317|bibcode=2000JPCRD..29.1141A}} * {{cite journal|first=Dennis|last=Barnum|year=2003|title=Some history of nitrates|journal=Journal of Chemical Education|volume=80|issue=12| pages=1393–|doi=10.1021/ed080p1393|bibcode=2003JChEd..80.1393B}} * Jones, Grinnell (1920). "Nitrogen: Its Fixation, Its Uses in Peace and War". ''The Quarterly Journal of Economics''. '''34''' (3): 391–431. * {{cite book|first1=J. W.|last1=Mullin|title=Crystallization|url=https://books.google.com/books?id=TiVuQgAACAAJ|year=1997|publisher=Butterworth-Heinemann|isbn=978-0-7506-3759-6}}

==External links== * [https://www.atsdr.cdc.gov/csem/csem.html 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] * Calculators: [http://www.aim.env.uea.ac.uk/aim/surftens/surftens.php surface tensions], and [http://www.aim.env.uea.ac.uk/aim/density/density_electrolyte.php densities, molarities and molalities] of aqueous sodium nitrate

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Category:Deliquescent materials Category:Nitrate minerals Category:Nitrates Category:Oxidizing agents Category:Preservatives Category:Pyrotechnic oxidizers Category:Sodium compounds Category:Sodium minerals