Sodium nitrate
From Wikipedia, the free encyclopedia
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General |
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| Name | Sodium nitrate | |
| Chemical formula | NaNO3 | |
| Appearance | White powder or colorless crystals | |
| CAS number | [7631-99-4] | |
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Physical |
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| Formula weight | 84.9947 amu | |
| Melting point | 580 K (307 °C) | |
| Boiling point | decomposes at 653 K (380 °C) | |
| Density | 2.3 ×103 kg/m3 | |
| Crystal structure | Trigonal | |
| Solubility | 92 g in 100mL water | |
| Critical relative humidity | 72.4% (30 °C) | |
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Thermochemistry |
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| ΔfH0liquid | -452 kJ/mol | |
| ΔfH0solid | -468 kJ/mol | |
| S0solid | 117 J/mol·K | |
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Safety |
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| Ingestion | May cause gastroenteritis and abdominal pains. | |
| NFPA 704 |
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| Inhalation | respiratory irritation | |
| Skin | May cause irritation. | |
| Eyes | May cause irritation. | |
| More info | MSDS | |
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SI units were used where possible. Unless otherwise stated, standard conditions were used. |
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Sodium nitrate (not to be confused with sodium nitride) is a type of salt (NaNO3) which has long been used as an ingredient in fertilizers, explosives and in solid rocket propellants, as well as in glass and pottery enamel, and as a food preservative (such as in hot dogs), and has been mined extensively for those purposes. It is also variously known as caliche, Chile saltpeter, saltpeter, and soda niter.
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. The former Chilean saltpeter mining communities of Humberstone and Santa Laura were declared Unesco World Heritage sites in 2005.
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.
Sodium nitrate is also manufactured synthetically by reacting nitric acid with soda ash.
[edit] Applications
Sodium nitrate was used extensively as a fertilizer and a raw material for the manufacture of gunpowder in the late nineteenth century. 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 value of Chile saltpeter declined dramatically in the first decades of the twentieth century after cheaper chemical means were found to make fertilizers and explosives. Sodium nitrate also has antimicrobial properties when used as a food preservative. It is found naturally in leafy green vegetables. It has possible health benefits for increasing oxygen to blood,[citation needed] as well as known health side effects in particular at high doses. Side effects may include increased risk of cancer (if intake occurs together with proteins, which builds carcinogenic nitrosamines), where according to MEDEM the US-NAS found no such evidence in experiments with laboratory animals. In case of overdosage the local poison control center is the contact of choice.
It can be used in the production of nitric acid by combining with sulfuric acid and subsequent separation through fractional distillation of the nitric acid, leaving behind a residue of sodium bisulfate.
Less common applications include an oxidizer used in gunpowder, in blackpowder rockets, and as replacement for potassium nitrate.
It can be used as a Phase Change Material.
