Sodium nitrate

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Sodium nitrate
Dusičnan sodný.JPG
NaNitrate.png Sodium-nitrate-unit-cell-3D-balls.png
Identifiers
CAS number 7631-99-4 YesY
PubChem 24268
ChemSpider 22688 YesY
UNII 8M4L3H2ZVZ YesY
UN number 1498
ChEMBL CHEMBL1644698 N
RTECS number WC5600000
Jmol-3D images Image 1
Properties
Molecular formula NaNO3
Molar mass 84.9947 g/mol
Appearance White powder or colorless crystals
Odor sweet
Density 2.257 g/cm3, solid
Melting point 308 °C
Boiling point 380 °C, decomposes
Solubility in water 73 g/100 mL (0°C)
91.2 g/100 mL (25 °C)
180 g/100 mL (100 °C)
Solubility very soluble in ammonia; soluble in alcohol
Refractive index (nD) 1.587 (trigonal)
1.336 (rhombohedral)
Structure
Crystal structure trigonal and rhombohedral
Thermochemistry
Std molar
entropy
So298
116 J·mol−1·K−1[1]
Std enthalpy of
formation
ΔfHo298
−467 kJ·mol−1[1]
Hazards
MSDS ICSC 0185
EU Index Not listed
Main hazards Oxidant, irritant
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazard OX: Oxidizer. E.g., potassium perchlorateNFPA 704 four-colored diamond
Flash point Non-flammable
LD50 3236 mg/kg
Related compounds
Other anions Sodium nitrite
Other cations Lithium nitrate
Potassium nitrate
Rubidium nitrate
Caesium nitrate
Related compounds Sodium sulfate
Sodium chloride
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

Sodium nitrate is the chemical compound with the formula NaNO3. This salt is also known as Chile saltpeter or Peru saltpeter (due to the large deposits found in each country) 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 solid which is 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 and smoke bombs, glass and pottery enamels, food preservatives, and solid rocket propellant. It has been mined extensively for these purposes.

History[edit]

The first shipment of Chile saltpeter to Europe arrived in England in 1820 or 1825, but did not find any buyers and was dumped at sea in order to avoid customs toll.[2][3] With time, however, the mining of South American saltpeter became a profitable business (in 1859, England alone consumed 47,000 metric tons[3]). Chile fought against the allies Peru and Bolivia in the War of the Pacific 1879-1884 and took over the richest deposits. In 1919, Ralph Walter Graystone Wyckoff determined its crystal structure using X-ray crystallography.

Sources[edit]

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.[4] 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,[citation needed] with active mines in such locations as Pedro de Valdivia, María Elena and Pampa Blanca, and there it used to be called white gold.[citation needed] 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.

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 → CO2 + H2O + NaNO3

or also by neutralizing it with sodium hydroxide, but the 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

Applications[edit]

Sodium nitrate was used extensively as a fertilizer and a raw material for the manufacture of gunpowder in the late 19th century. It can be combined with iron hydroxide to make a synthetic resin.[citation needed]

Sodium nitrate can be used in the production of nitric acid by combining it with sulfuric acid over heat or an extended period of time due to sulfuric acid's highly exothermic reaction with water, as the sodium nitrate must first be converted via thermal decomposition to sodium nitrite:

2NaNO
3
→ 2NaNO
2
+ O
2

The combination of sodium nitrite as a result reacts with sulfuric acid to produce nitrous acid and sodium sulfate:

2NaNO
2
+ H
2
SO
4
→ 2HNO
2
+ Na
2
SO
4

Nitrogen dioxide is produced from the decomposition of nitrous acid under normal conditions:

2HNO2NO
2
+ NO + H
2
O

The resulting nitrogen dioxide then reacts with atmospherical gaseous water and is routed through a condenser or a fractional distillation apparatus. The yielded mixture of nitric acid and unreacted nitrogen dioxide vestiges are condensed:

2NO
2
+ H
2
O
HNO
3
+ HNO
2

Hobbyist gold refiners use sodium nitrate to make a hybrid aqua regia that dissolves gold and other metals.

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,[5] USA[6] and Australia and New Zealand.[7] Sodium nitrate should not be confused with sodium nitrite, which is also a common food additive and preservative used for example, in deli meats.

Less common applications include as an oxidizer in fireworks replacing potassium nitrate commonly found in black powder and as a component in instant cold packs.[8]

Sodium nitrate is used together with potassium nitrate and calcium nitrate for heat storage and, more recently, for heat transfer in solar power plants. A mixture of sodium nitrate, calcium nitrate and potassium nitrate is used as energy storage material in prototype plants, such as Andasol Solar Power Station and the Archimede project.

It is also used in the wastewater industry for facultative microorganism respiration. Nitrosomonas, a genus of microorganisms, consumes nitrate in preference to oxygen, enabling it to grow more rapidly in the wastewater to be treated.

Sodium Nitrate is also sometimes used by marine aquarists who utilize carbon dosing techniques. It is used to increase nitrate levels in the water and promote bacterial growth.

Dental use[edit]

Mouthwash and gels containing Sodium Nitrate are used in treatment of dentine hypersensitivity.[citation needed]

Health concerns[edit]

Advertisement for sodium nitrate from Chile on a wall of a village in the Algarve area of Portugal

Studies have shown a link between increased levels of nitrates and increased deaths from certain diseases including Alzheimer's, diabetes mellitus and Parkinson's, possibly through the damaging effect of nitrosamines on DNA, however, little is done to control for other possible causes in the epistemological results.[9] Nitrosamines, formed in cured meats containing sodium nitrate and nitrite, have been linked to gastric cancer and oesophageal cancer.[10] Sodium nitrate and nitrite are associated with a higher risk of colorectal cancer.[11] World Cancer Research Fund UK,[12] states that one of the reasons that processed meat increases the risk of colon cancer is its content of nitrate. 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 NOCs (nitroso compounds). NOCs can be formed either when meat is cured or in the body as meat is digested.

See also[edit]

Notes and references[edit]

  1. ^ a b Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A23. ISBN 0-618-94690-X. 
  2. ^ S. H. Baekeland "Några sidor af den kemiska industrien" (1914) Svensk Kemisk Tidskrift, p. 140.
  3. ^ a b Friedrich Georg Wieck, Uppfinningarnas bok (1873, Swedish translation of Buch der Erfindungen), vol. 4, p. 473.
  4. ^ 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
  5. ^ UK Food Standards Agency: "Current EU approved additives and their E Numbers". Retrieved 2011-10-27. 
  6. ^ US Food and Drug Administration: "Listing of Food Additives Status Part II". Retrieved 2011-10-27. 
  7. ^ Australia New Zealand Food Standards Code"Standard 1.2.4 - Labelling of ingredients". Retrieved 2011-10-27. 
  8. ^ Albert A. Robbins "Chemical freezing package" U.S. Patent 2,898,744, Issue date: August 1959
  9. ^ 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 : JAD 17 (3): 519–29. doi:10.3233/JAD-2009-1070 (inactive 2014-03-22). PMID 19363256. 
  10. ^ http://ecnis.openrepository.com/ecnis/handle/10146/25215
  11. ^ Cross, AJ; Ferrucci, LM; Risch, A; Graubard, BI; Ward, MH; Park, Y; Hollenbeck, AR; Schatzkin, A; Sinha, R (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. 
  12. ^ "Why does processed meat increase bowel cancer risk?", World Cancer Research Fund (2010) accessdate 2010-03-06

Further reading[edit]

External links[edit]

HNO3 He
LiNO3 Be(NO3)2 B(NO3)3 C N O F Ne
NaNO3 Mg(NO3)2 Al(NO3)3 Si P S ClONO2 Ar
KNO3 Ca(NO3)2 Sc(NO3)3 Ti V Cr(NO3)3 Mn(NO3)2 Fe(NO3)3 Co(NO3)2, Co(NO3)3 Ni(NO3)2 Cu(NO3)2 Zn(NO3)2 Ga(NO3)3 Ge As Se Br Kr
RbNO3 Sr(NO3)2 Y Zr Nb Mo Tc Ru Rh Pd(NO3)2 AgNO3 Cd(NO3)2 In Sn Sb Te I Xe
CsNO3 Ba(NO3)2 Hf Ta W Re Os Ir Pt Au Hg2(NO3)2, Hg(NO3)2 Tl(NO3)3 Pb(NO3)2 Bi(NO3)3 Po At Rn
Fr Ra Rf Db Sg Bh Hs Mt Ds Rg Cn Uut Fl Uup Lv Uus Uuo
La Ce Pr Nd Pm Sm Eu Gd(NO3)3 Tb Dy Ho Er Tm Yb Lu
Ac Th Pa UO2(NO3)2 Np Pu Am Cm Bk Cf Es Fm Md No Lr