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Potassium nitrate

2007 Schools Wikipedia Selection. Related subjects: Chemical compounds

                     Potassium nitrate
                    Potassium nitrate
                          General
   Other names         Saltpetre
                       Nitrate of potash
   Molecular formula   KNO[3]
   Molar mass          101.1032 g/mol
   Appearance          white solid
   CAS number          [7757-79-1]
                        Properties
   Density and phase   2.1 g/cm³, solid
   Solubility in water 35.7 g/100 ml (25 °C)
   Melting point       334 °C
   Boiling point       400 °C decomp.
                         Structure
   Coordination
   geometry             ?
   Crystal structure   Orthorhombic, Aragonite
                          Hazards
   MSDS                External MSDS
   EU classification
   NFPA 704

                       0
                       1
                       3
                       ox
   R-phrases
   S-phrases
                  Supplementary data page
   Structure and
   properties          n, ε[r], etc.
   Thermodynamic
   data                Phase behaviour
                       Solid, liquid, gas
   Spectral data       UV, IR, NMR, MS
                     Related compounds
   Other anions        Potassium nitrite
   Other cations       Lithium nitrate
                       Sodium nitrate
                       Rubidium nitrate
                       Caesium nitrate
     Except where noted otherwise, data are given for
   materials in their standard state (at 25 °C, 100 kPa)
   Infobox disclaimer and references
   The crystal structure of KNO3
   Enlarge
   The crystal structure of KNO[3]

   The chemical compound potassium nitrate is a naturally occurring
   mineral source of nitrogen. It is a nitrate with chemical formula
   KNO[3].

   Its common names include saltpetre (from Medieval Latin sal petrae:
   "stone salt" or possibly "Salt of Petra"), American English salt peter,
   Nitrate of potash and nitre. The name salt peter is also applied to
   sodium nitrate.

Description

   Potassium nitrate is the oxidizing (oxygen-supplying) component of
   black powder. Prior to the large-scale industrial fixation of nitrogen
   through 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. It was and is also used
   as a component in some fertilizers. When used by itself as a
   fertilizer, it has an NPK rating of 13-0-44 (indicating 13%, 0%, and
   44% of nitrogen, phosphorus, and potassium, by mass, respectively).

Manufacture

   Historically, nitre-beds were prepared by mixing manure with either
   mortar or wood ashes, common earth and organic materials such as straw
   to give porosity to a compost pile typically 1.5 metres high by 2
   metres wide by 5 metres long. The heap was usually under a cover from
   the rain, kept moist with urine, turned often to accelerate the
   decomposition and leached with water after approximately one year. The
   liquid containing various nitrates was then converted with wood ashes
   to potassium nitrates, crystallized and refined for use in gunpowder.
   Today, most potassium nitrate comes from the vast deposits of sodium
   nitrate (NaNO[3], nitratine) in the Chilean deserts. The sodium nitrate
   is purified and then reacted in solution with potassium chloride (KCl,
   sylvite), from which the less-soluble potassium nitrate is precipitated
   out.

   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.

Applications

   One of the most useful applications of potassium nitrate is in the
   production 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 fertilizer, in model rocket
   propellant, and in several fireworks such as smoke bombs, in which a
   mixture with sugar produces a smoke cloud of 600 times their own
   volume. The ratio for smoke bombs using sucrose (powdered sugar) and
   potassium nitrate is 40(C[12]H[22]O[11]):60(KNO[3]). It can be used as
   is, or carefully melted together using a hot plate.

   In the process of food preservation, potassium nitrate is a rare
   ingredient of salted meat, but there are theories indicating that using
   nitrates in meats can cause cancer. As a preservative it can be known
   as E252.

   Potassium Nitrate is also a main component in stump remover; it
   accelerates the natural decomposition of the stump. Stump remover is
   usually about 98% pure KNO[3], and is a common source of KNO[3].

   It has also been used in the manufacture of ice cream and can be found
   in some toothpastes for sensitive teeth. Recently, the use of potassium
   nitrate in toothpastes for sensitive teeth has increased dramatically,
   despite the fact that it has not been conclusively shown to help dental
   hypersensitivity.

   A popular misconception is that potassium nitrate is an anaphrodisiac
   and was added to food in all-male institutions. In fact, potassium
   nitrate has no such effect in humans.

   Although potassium nitrate is used in gunpowder, by itself, potassium
   nitrate is not combustible or flammable.
   Retrieved from " http://en.wikipedia.org/wiki/Potassium_nitrate"
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   with only minor checks and changes (see www.wikipedia.org for details
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