Saltpeter

</table> The chemical compoundpotassium nitrate is a naturally occurring mineral source of nitrogen. It is a nitrate with chemical formula K N O₃. Its common names include saltpetre (from Medieval Latin sal petrae: "stone salt" or possibly "salt of Petra"), 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 Potassium nitrate was the deposits crystallising from cave walls or the drainings of decomposing organic material. Dung-heaps were a particularly common source: ammonia from the decomposition of urea and other nitrogenous materials would undergo bacterial oxidation to produce nitrate. One of the most useful applications of potassium nitrate is in the production of of nitric acid, by adding concentrated sulfuric acid to an aqueous solution of potassium nitrate, yielding nitric acid and potassium sulfate 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-Potassium nitrate mix which gives rise to a lot of smoke. In the process of food preservation, potassium nitrate is a common ingredient of salted meat. 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 Potassium nitrate 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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Nitric acid

**Properties**
General
Name	Potassium nitrate
Chemical formula	K NO₃
Appearance	White or dirty gray solid
Physical
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
Thermochemistry
Δ_fH⁰_gas	? kJ/mol
Δ_fH⁰_liquid	-483 kJ/mol
Δ_fH⁰_solid	-495 kJ/mol
S⁰_{gas, 1 bar}	? J/mol·K
S⁰_{liquid, 1 bar}	? J/mol·K
S⁰_solid	? J/mol·K
Safety
Ingestion	May cause GI irritation, nausea, vomiting, diarrhea.
Inhalation	Irritation, long term exposure may be fatal.
Skin	Low hazard.
Eyes	Low hazard.
SI units were used where possible. Unless otherwise stated, standard conditions were used. Disclaimer and references </font>


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