The Potassium nitrate reference article from the English Wikipedia on 24-Jul-2004
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Potassium nitrate

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Name Potassium nitrate
Chemical formula KNO3
Appearance White or dirty gray solid


Formula weight 101.1 amu
Melting point 607 K (334 °C)
Boiling point decomposes at 673 K (400 °C)
Density 2.1 ×103 kg/m3
Crystal structure Aragonite
Solubility 38 g in 100g water


ΔfH0gas ? kJ/mol
ΔfH0liquid -483 kJ/mol
ΔfH0solid -495 kJ/mol
S0gas, 1 bar ? J/mol·K
S0liquid, 1 bar ? J/mol·K
S0solid ? J/mol·K


Ingestion May cause GI irritation, nausea, vomiting, diarrhea.
Inhalation Irritation, long term exposure may be fatal.
Skin Low hazard.
Eyes Low hazard.
More info Hazardous Chemical Database
SI units were used where possible. Unless otherwise stated, standard conditions were used.

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The chemical compound potassium nitrate is a naturally occurring mineral source of nitrogen. It is a nitrate with chemical formula KNO3.

Its common names include saltpetre (from 14th century medieval latin sal petrae: "stone salt"), American English saltpeter, Chilean saltpetre, and nitre. The name "saltpeter" is also applied to sodium nitrate.

It is the oxidising (oxygen-supplying) component of gunpowder. Prior to the large-scale industrial fixation of nitrogen (the Haber process), a major source of saltpetre was the deposits crystallising from cave walls or the drainings of decomposing organic material.

One of the most useful applications of potassium nitrate is in the production of of nitric acid, by adding concentrated sulphuric acid to an aqueous solution of potassium nitrate, yielding nitric acid and potassium chloride which are separated through fractional distillation.

Potassium nitrate is also used as a fertiliser, as a model rocket propellant, and for certain pyrotechnic combinations, such as the renowned sugar-saltpetre mix which gives rise to a lot of smoke.

In England, the privilege of manufacturing explosives had been in the hands of the family of John Evelyn, the celebrated diarist, as a crown monopoly since before 1588.

An urban legend holds that soldiers, sailors, and other young men in institutional situations are secretly administered saltpetre in their food, especially during bootcamp, to suppress their sexual urges. It is conjectured that the troops were employing a folk etymology and replacing "salt" with "soft". The reduction in sexual urges does in fact occur, but is caused by physical exhaustion related to intense training.

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