Sodium nitrate

Last updated
Sodium nitrate
Dusicnan sodny.JPG
NaNitrate.png
Sodium-nitrate-unit-cell-3D-balls.png
Names
IUPAC name
Sodium nitrate
Other names
Peru saltpeter
Soda niter
cubic niter
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.028.686 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 231-554-3
E number E251 (preservatives)
PubChem CID
RTECS number
  • WC5600000
UNII
UN number 1498
  • InChI=1S/NO3.Na/c2-1(3)4;/q-1;+1 Yes check.svgY
    Key: VWDWKYIASSYTQR-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/NO3.Na/c2-1(3)4;/q-1;+1
    Key: VWDWKYIASSYTQR-UHFFFAOYAL
  • [Na+].[O-][N+]([O-])=O
Properties
NaNO3
Molar mass 84.9947 g/mol
AppearanceWhite powder or colorless crystals
Odor sweet
Density 2.257 g/cm3, solid
Melting point 308 °C (586 °F; 581 K)
Boiling point 380 °C (716 °F; 653 K) decomposes
73 g/100 g water (0 °C)
91.2 g/100 g water (25 °C) [1] [2]
180 g/100 g water (100 °C)
Solubility very soluble in ammonia, hydrazine
soluble in alcohol
slightly soluble in pyridine
insoluble in acetone
25.6·10−6 cm3/mol
1.587 (trigonal)
1.336 (rhombohedral)
Viscosity 2.85 cP (317 °C)
Structure
trigonal and rhombohedral
Thermochemistry
93.05 J/(mol K)
Std molar
entropy
(S298)
116 J/(mol K) [3]
−467 kJ/mol [3]
−365.9 kJ/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
Harmful (Xn)
Oxidant (O)
GHS labelling:
GHS-pictogram-exclam.svg GHS-pictogram-rondflam.svg
NFPA 704 (fire diamond)
NFPA 704.svgHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazard OX: Oxidizer. E.g. potassium perchlorate
1
0
0
OX
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
3236 mg/kg
Safety data sheet (SDS) ICSC 0185
Related compounds
Other anions
Sodium nitrite
Other cations
Lithium nitrate
Potassium nitrate
Rubidium nitrate
Caesium nitrate
Related compounds
Sodium sulfate
Sodium chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Sodium nitrate is the chemical compound with the formula Na N O
3
. This alkali metal nitrate salt is also known as Chile saltpeter (large deposits of which were historically mined in Chile) [4] [5] to distinguish it from ordinary saltpeter, potassium nitrate. The mineral form is also known as nitratine, nitratite or soda niter.

Contents

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. [6] [7] With time, however, the mining of South American saltpeter became a profitable business (in 1859, England alone consumed 47,000 metric tons). [7] 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.

Occurrence

Advertisement for sodium nitrate fertilizer from Chile on a wall of a village in the Algarve area of Portugal
Mines of Chile, green is sodium nitrate area Chile Principle Producing Mines - DPLA - 6e7888f5d8ec26604ddd9e7d2928a0dd.jpg
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. [8] 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. [9] 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. [4] [5] 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 °C) and high heat capacities. These properties are suitable for thermally annealing metals and for storing thermal energy in solar applications. [10]

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, [11] US [12] and Australia and New Zealand. [13] 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. [14] [15] Examples of the applications of sodium nitrate used for thermal energy storage include solar thermal power technologies and direct steam generating parabolic troughs. [14]

Steel coating

Sodium nitrate is used in a steel coating process in which it forms a surface of magnetite layer. [16]

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. [17] Nitrosamines, formed in cured meats containing sodium nitrate and nitrite, have been linked to gastric cancer and esophageal cancer. [18] Sodium nitrate and nitrite are associated with a higher risk of colorectal cancer. [19]

Substantial evidence in recent decades, facilitated by an increased understanding of pathological processes and science, exists in support of the theory that processed meat increases the risk of colon cancer and that this is due to the nitrate content. A small amount of the nitrate added to meat as a preservative breaks down into nitrite, in addition to any nitrite that may also be added. The nitrite then reacts with protein-rich foods (such as meat) to produce carcinogenic NOCs (nitroso compounds). NOCs can be formed either when meat is cured or in the body as meat is digested. [20]

However, several things complicate the otherwise straightforward understanding that "nitrates in food raise the risk of cancer". Processed meats have no fiber, vitamins, or phytochemical antioxidants, are high in sodium, may contain high fat, and are often fried or cooked at a temperature sufficient to degrade protein into nitrosamines. Nitrates are key intermediates and effectors in the primary vasculature signaling which is necessary for all mammals to survive. [21]

See also

Related Research Articles

<span class="mw-page-title-main">Nitrate</span> Polyatomic ion (NO₃, charge –1) found in explosives and fertilisers

Nitrate is a polyatomic ion with the chemical formula NO
3
. Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are soluble in water. An example of an insoluble nitrate is bismuth oxynitrate.

A preservative is a substance or a chemical that is added to products such as food products, beverages, pharmaceutical drugs, paints, biological samples, cosmetics, wood, and many other products to prevent decomposition by microbial growth or by undesirable chemical changes. In general, preservation is implemented in two modes, chemical and physical. Chemical preservation entails adding chemical compounds to the product. Physical preservation entails processes such as refrigeration or drying. Preservative food additives reduce the risk of foodborne infections, decrease microbial spoilage, and preserve fresh attributes and nutritional quality. Some physical techniques for food preservation include dehydration, UV-C radiation, freeze-drying, and refrigeration. Chemical preservation and physical preservation techniques are sometimes combined.

<span class="mw-page-title-main">Potassium nitrate</span> Chemical compound

Potassium nitrate is a chemical compound with a sharp, salty, bitter taste and the chemical formula KNO
3
. It is an ionic salt of potassium ions K+ and nitrate ions NO3, and is therefore an alkali metal nitrate. It occurs in nature as a mineral, niter (or nitre outside the US). It is a source of nitrogen, and nitrogen was named after niter. Potassium nitrate is one of several nitrogen-containing compounds collectively referred to as saltpetre (or saltpeter in the US).

<span class="mw-page-title-main">Ammonium nitrate</span> Chemical compound with formula NH4NO3

Ammonium nitrate is a chemical compound with the formula NH4NO3. It is a white crystalline salt consisting of ions of ammonium and nitrate. It is highly soluble in water and hygroscopic as a solid, although it does not form hydrates. It is predominantly used in agriculture as a high-nitrogen fertilizer.

The nitrite ion has the chemical formula NO
2
. Nitrite is widely used throughout chemical and pharmaceutical industries. The nitrite anion is a pervasive intermediate in the nitrogen cycle in nature. The name nitrite also refers to organic compounds having the –ONO group, which are esters of nitrous acid.

<span class="mw-page-title-main">Sodium nitrite</span> Chemical compound

Sodium nitrite is an inorganic compound with the chemical formula NaNO2. It is a white to slightly yellowish crystalline powder that is very soluble in water and is hygroscopic. From an industrial perspective, it is the most important nitrite salt. It is a precursor to a variety of organic compounds, such as pharmaceuticals, dyes, and pesticides, but it is probably best known as a food additive used in processed meats and in fish products.

<span class="mw-page-title-main">Nitrosamine</span> Organic compounds of the form >N–N=O

In organic chemistry, nitrosamines are organic compounds with the chemical structure R2N−N=O, where R is usually an alkyl group. They feature a nitroso group bonded to a deprotonated amine. Most nitrosamines are carcinogenic in nonhuman animals. A 2006 systematic review supports a "positive association between nitrite and nitrosamine intake and gastric cancer, between meat and processed meat intake and gastric cancer and oesophageal cancer, and between preserved fish, vegetable and smoked food intake and gastric cancer, but is not conclusive".

<span class="mw-page-title-main">Pancetta</span> Italian bacon made of pork belly meat

Pancetta is a salt-cured pork belly meat product in a category known as salume. In Italy, it is often used to add depth to soups and pastas.

<span class="mw-page-title-main">Calcium nitrate</span> Chemical compound

Calcium nitrate are inorganic compounds with the formula Ca(NO3)2(H2O)x. The anhydrous compound, which is rarely encountered, absorbs moisture from the air to give the tetrahydrate. Both anhydrous and hydrated forms are colourless salts. Hydrated calcium nitrate, also called Norgessalpeter (Norwegian salpeter), is mainly used as a component in fertilizers, but it has other applications. Nitrocalcite is the name for a mineral which is a hydrated calcium nitrate that forms as an efflorescence where manure contacts concrete or limestone in a dry environment as in stables or caverns. A variety of related salts are known including calcium ammonium nitrate decahydrate and calcium potassium nitrate decahydrate.

<span class="mw-page-title-main">Processed meat</span> Type of meat

Processed meat is considered to be any meat that has been modified in order to either improve its taste or to extend its shelf life. Methods of meat processing include salting, curing, fermentation, smoking, boiling, frying, and/or the addition of chemical preservatives. Processed meat is usually composed of pork or beef or, less frequently, poultry. It can also contain offal or meat by-products such as blood. Processed meat products include bacon, ham, sausages, salami, corned beef, jerky, hot dogs, lunch meat, canned meat, chicken nuggets, and meat-based sauces. Meat processing includes all the processes that change fresh meat with the exception of simple mechanical processes such as cutting, grinding or mixing.

<span class="mw-page-title-main">Sodium erythorbate</span> Chemical compound

Sodium erythorbate (C6H7NaO6) is a food additive used predominantly in meats, poultry, and soft drinks. Chemically, it is the sodium salt of erythorbic acid. When used in processed meat such as hot dogs and beef sticks, it increases the rate at which nitrite reduces to nitric oxide, thus facilitating a faster cure and retaining the pink coloring. As an antioxidant structurally related to vitamin C, it helps improve flavor stability and prevents the formation of carcinogenic nitrosamines. When used as a food additive, its E number is E316. The use of erythorbic acid and sodium erythorbate as a food preservative has increased greatly since the U.S. Food and Drug Administration banned the use of sulfites as preservatives in foods intended to be eaten fresh (such as ingredients for fresh salads) and as food processors have responded to the fact that some people are allergic to sulfites. It can also be found in bologna, and is occasionally used in beverages, baked goods, and potato salad. Sodium erythorbate is produced from sugars derived from different sources, such as beets, sugarcane, and corn. Sodium erythorbate is usually produced via a fermentation process from D-glucose by Pseudomonas fluorescens bacteria. Most syntheses proceed through the 2-keto-D-gluconic acid intermediate. An urban myth claims that sodium erythorbate is made from ground earthworms; however, there is no truth to the myth. It is thought that the origin of the legend comes from the similarity of the chemical name to the words earthworm and bait.

<span class="mw-page-title-main">Sausage making</span> Sausage production processes

The origins of meat preservation are lost to the ages but probably began when humans began to realize the preservative value of salt. Sausage making originally developed as a means to preserve and transport meat. Primitive societies learned that dried berries and spices could be added to dried meat. The procedure of stuffing meat into casings remains basically the same today, but sausage recipes have been greatly refined and sausage making has become a highly respected culinary art.

<span class="mw-page-title-main">Charcuterie</span> Branch of cooking of prepared meat products, primarily from pork

Charcuterie is a branch of French cuisine devoted to prepared meat products, such as bacon, ham, sausage, terrines, galantines, ballotines, pâtés, and confit, primarily from pork.

<span class="mw-page-title-main">Nitratine</span> Mineral form of sodium nitrate

Nitratine or nitratite, also known as cubic niter (UK: nitre), soda niter or Chile saltpeter (UK: Chile saltpetre), is a mineral, the naturally occurring form of sodium nitrate, NaNO3. Chemically it is the sodium analogue of saltpeter. Nitratine crystallizes in the trigonal system, but rarely occurs as well-formed crystals. It is isostructural with calcite. It is relatively soft and light with a Mohs hardness of 1.5 to 2 and a specific gravity of 2.24 to 2.29. Its refractive indices are nω = 1.587 and nε = 1.336.

<span class="mw-page-title-main">Nitroso</span> Class of functional groups with a –N=O group attached

In organic chemistry, nitroso refers to a functional group in which the nitric oxide group is attached to an organic moiety. As such, various nitroso groups can be categorized as C-nitroso compounds, S-nitroso compounds, N-nitroso compounds, and O-nitroso compounds.

The chemical element nitrogen is one of the most abundant elements in the universe and can form many compounds. It can take several oxidation states; but the most common oxidation states are -3 and +3. Nitrogen can form nitride and nitrate ions. It also forms a part of nitric acid and nitrate salts. Nitrogen compounds also have an important role in organic chemistry, as nitrogen is part of proteins, amino acids and adenosine triphosphate.

<span class="mw-page-title-main">Curing salt</span> Salt used in food preservation

Curing salt is used in meat processing to generate a pinkish shade and to extend shelf life. It is both a color agent and a means to facilitate food preservation as it prevents or slows spoilage by bacteria or fungus. Curing salts are generally a mixture of sodium chloride and sodium nitrite, and are used for pickling meats as part of the process to make sausage or cured meat such as ham, bacon, pastrami, corned beef, etc. Though it has been suggested that the reason for using nitrite-containing curing salt is to prevent botulism, a 2018 study by the British Meat Producers Association determined that legally permitted levels of nitrite have no effect on the growth of the Clostridium botulinum bacteria that causes botulism, in line with the UK's Advisory Committee on the Microbiological Safety of Food opinion that nitrites are not required to prevent C. botulinum growth and extend shelf life..

<span class="mw-page-title-main">Curing (food preservation)</span> Food preservation and flavouring processes based on drawing moisture out of the food by osmosis

Curing is any of various food preservation and flavoring processes of foods such as meat, fish and vegetables, by the addition of salt, with the aim of drawing moisture out of the food by the process of osmosis. Because curing increases the solute concentration in the food and hence decreases its water potential, the food becomes inhospitable for the microbe growth that causes food spoilage. Curing can be traced back to antiquity, and was the primary method of preserving meat and fish until the late 19th century. Dehydration was the earliest form of food curing. Many curing processes also involve smoking, spicing, cooking, or the addition of combinations of sugar, nitrate, and nitrite.

<span class="mw-page-title-main">Cured fish</span> Fish subjected to fermentation, pickling or smoking

Cured fish is fish which has been cured by subjecting it to fermentation, pickling, smoking, or some combination of these before it is eaten. These food preservation processes can include adding salt, nitrates, nitrite or sugar, can involve smoking and flavoring the fish, and may include cooking it. The earliest form of curing fish was dehydration. Other methods, such as smoking fish or salt-curing also go back for thousands of years. The term "cure" is derived from the Latin curare, meaning to take care of. It was first recorded in reference to fish in 1743.

In biochemistry, nitrosamines are a class of compounds that can form during food digestion. The presence of their precursors, nitrites, in cured meats, is controversial, because of a small connection to cancer risk.

References

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  2. "Sodium nitrate". PubChem. Retrieved 11 June 2021.
  3. 1 2 Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A23. ISBN   978-0-618-94690-7.
  4. 1 2 "The Nitrate Towns of Chile". Atlas Obscura. Retrieved 27 May 2019.
  5. 1 2 Mutic, Anja (26 October 2012). "The ghost towns of northern Chile". Washington Post. Retrieved 27 May 2019.
  6. S. H. Baekeland "Några sidor af den kemiska industrien" (1914) Svensk Kemisk Tidskrift, p. 140.
  7. 1 2 Friedrich Georg Wieck, Uppfinningarnas bok (1873, Swedish translation of Buch der Erfindungen), vol. 4, p. 473.
  8. 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.
  9. Arias, Jaime (24 Jul 2003). On the Origin of Saltpeter, Northern Chile Coast. International Union for Quaternary Research. Archived from the original on 4 March 2016. Retrieved 19 Aug 2018.
  10. Laue, Wolfgang; Thiemann, Michael; Scheibler, Erich; Wiegand, Karl (2000). "Nitrates and Nitrites". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a17_265. ISBN   978-3527306732.
  11. UK Food Standards Agency: "Current EU approved additives and their E Numbers" . Retrieved 2011-10-27.
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  13. Australia New Zealand Food Standards Code "Standard 1.2.4 – Labelling of ingredients". 8 September 2011. Retrieved 2011-10-27.
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  15. ICTAC Working Group; Sabbah, R.; et al. (1999-06-14). "Reference materials for calorimetry and differential thermal analysis". Thermochimica Acta. 331 (2): 93–204. doi:10.1016/S0040-6031(99)00009-X. ISSN   0040-6031.
  16. Fauzi, Ahmad Asyraf Bin Ahmad (2014). Production of Magnetite Thin Film Over Steel Substrate Using Hot Alkaline Nitrate Blackening Method. 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).
  17. De La Monte, SM; Neusner, A; Chu, J; Lawton, M (2009). "Epidemilogical trends strongly suggest exposures as etiologic agents in the pathogenesis of sporadic Alzheimer's disease, diabetes mellitus, and non-alcoholic steatohepatitis". Journal of Alzheimer's Disease. 17 (3): 519–29. doi:10.3233/JAD-2009-1070. PMC   4551511 . PMID   19363256.
  18. Jakszyn, Paula; Gonzalez, Carlos-Alberto (21 Jul 2006). "Nitrosamine and related food intake and gastric and oesophageal cancer risk: a systematic review of the epidemiological evidence". World Journal of Gastroenterology. 12 (27): 4296–4303. doi: 10.3748/wjg.v12.i27.4296 . PMC   4087738 . PMID   16865769.
  19. Cross, AJ; Ferrucci, LM; Risch, A; et al. (2010). "A large prospective study of meat consumption and colorectal cancer risk: An investigation of potential mechanisms underlying this association". Cancer Research. 70 (6): 2406–14. doi:10.1158/0008-5472.CAN-09-3929. PMC   2840051 . PMID   20215514.
  20. "The Associations between Food, Nutrition and Physical Activity and the Risk of Colorectal Cancer", Archived 2019-07-26 at the Wayback Machine World Cancer Research Fund (2010)
  21. Machha, Ajay; Schechter, Alan N. (August 2011). "Dietary nitrite and nitrate: a review of potential mechanisms of cardiovascular benefits". European Journal of Nutrition. 50 (5): 293–303. doi:10.1007/s00394-011-0192-5. ISSN   1436-6207. PMC   3489477 . PMID   21626413.

Further reading