'''Potassium perchlorate''', a [[perchlorate]] [[salt (chemistry)|salt]] with the chemical formula [[potassium|K]][[chlorine|Cl]][[oxygen|O]]<sub>4</sub>, is a strong [[oxidizing agent|oxidizer]]. It is a colorless, crystalline substance that melts at about 610 °C. It is one of the most common oxidizers used in fireworks, ammunition percussion caps, explosive primers, and is used variously in propellants, flash compositions, stars, and sparklers. It has been used as a solid rocket propellant, though in that application it has mostly been replaced by the higher performance [[ammonium perchlorate]]. [[potassium|K]][[chlorine|Cl]][[oxygen|O]]<sub>4</sub> has the lowest [[solubility]] of all perchlorates (1.5 g in 100 g of water at 25 °C).<ref name=jtbaker/>
==Reactions==
'''Potassium perchlorate''' is the inorganic [[salt (chemistry)|salt]] with the chemical formula [[potassium|K]][[chlorine|Cl]][[oxygen|O<sub>4</sub>]]. Like other [[perchlorate]]s, this salt is a strong [[oxidizing agent|oxidizer]] although it usually reacts very slowly with organic substances. This usually obtained as a colorless, crystalline solid is a common oxidizer used in [[fireworks]], [[ammunition]] [[percussion cap]]s, [[explosive primer]]s, and is used variously in [[propellant]]s, [[flash powder|flash compositions]], stars, and [[sparklers]]. It has been used as a [[solid rocket]] propellant, although in that application it has mostly been replaced by the higher performance [[ammonium perchlorate]]. KClO<sub>4</sub> has the lowest [[solubility]] of the [[alkali metal]] perchlorates (1.5 g in 100 mL of water at 25 °C).<ref name=jtbaker />
As an oxidizer, KClO<sub>4</sub> reacts with a wide variety of fuels. A common example is [[glucose]], C<sub>6</sub>H<sub>12</sub>O<sub>6</sub>.
[[File:Perclorato de Potássio.jpg|200px|thumbnail|left|Potassium perchlorate in crystal form]]
KClO<sub>4</sub> is prepared industrially by treating an aqueous solution of [[sodium perchlorate]] with KCl. This single precipitation reaction exploits the low solubility of KClO<sub>4</sub>, which is about 100 times less than the solubility of NaClO<sub>4</sub> (209.6 g/100 mL at 25 °C).<ref>Helmut Vogt, Jan Balej, John E. Bennett, Peter Wintzer, Saeed Akbar Sheikh, Patrizio Gallone "Chlorine Oxides and Chlorine Oxygen Acids" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. {{DOI|10.1002/14356007.a06_483}}</ref> It can also be produced by the reaction of perchloric acid with potassium hydroxide, however this is not used widely, due to the dangers of perchloric acid.
When mixed with cane sugar, it can be used as a low explosive, if the necessary confinement is provided. Otherwise the mixture will simply deflagrate with an intense purple flame indicative of [[potassium]] salts. Flash compositions used in firecrackers usually consist of fine [[aluminium]] powder mixed with potassium perchlorate.
==Oxidizing properties==
KClO<sub>4</sub> is an oxidizer in the sense that it exothermically transfers [[oxygen]] to [[combustible]] materials, greatly increasing their rate of combustion relative to that in [[air]]. Thus, with [[glucose]] it gives carbon dioxide:
Potassium perchlorate can be used safely in the presence of [[sulfur]]; however, [[potassium chlorate]] cannot. The common explanation for this is that the sulfur will, given time, produce minute quantities of [[sulfurous acid]] and [[sulfuric acid]]. These will, in turn, react with potassium chlorate to produce [[chloric acid]], which is highly unstable and can lead to premature ignition of the composition. The corresponding acid of potassium perchlorate, [[perchloric acid]], is stable enough as to prevent spontaneous ignition.
The conversion of solid glucose into hot gaseous CO<sub>2</sub> is the basis of the explosive force of this and other such mixtures. Even with [[cane sugar]], KClO<sub>4</sub> yields a low explosive, provided the necessary confinement. Otherwise such mixtures simply [[deflagrate]] with an intense purple flame characteristic of [[potassium]]. Flash compositions used in [[firecracker]]s usually consist of fine [[aluminium]] powder mixed with potassium perchlorate.
==Production==
As an oxidizer, potassium perchlorate can be used safely in the presence of [[sulfur]], whereas [[potassium chlorate]] cannot. The greater reactivity of chlorate is typical – perchlorates are kinetically poorer oxidants. Chlorate produces [[chloric acid]], which is highly unstable and can lead to premature ignition of the composition. Correspondingly, [[perchloric acid]] is quite stable.<ref>Greenwood, N. N.; Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.</ref>
Potassium perchlorate is produced by double decomposition reaction with [[sodium perchlorate]] and [[potassium chloride]]. Sodium perchlorate is manufactured by [[anodic oxidation]] of [[sodium chloride]].<ref>[http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/encyperc.html Perchlorate Production]</ref>
==In medicine==
==In medicine==
Potassium perchlorate can be used as a potent [[antithyroid]] agent used to treat [[hyperthyroidism]], usually in combination with one other medication.
Potassium perchlorate can be used as an [[antithyroid]] agent used to treat [[hyperthyroidism]], usually in combination with one other medication. This application exploits the similar ionic radii and hydrophilicity of perchlorate and [[iodide]].
==Other Uses==
Since 2005, a cartridge with potassium perchlorate mixed with [[anthracene]] and [[sulfur]] is used for generating the black smoke signalling the failure of reaching a two-thirds majority needed for the election of new pope by a papal [[conclave]].
KClO4 is prepared industrially by treating an aqueous solution of sodium perchlorate with KCl. This single precipitation reaction exploits the low solubility of KClO4, which is about 100 times less than the solubility of NaClO4 (209.6 g/100 mL at 25 °C).[6] It can also be produced by the reaction of perchloric acid with potassium hydroxide, however this is not used widely, due to the dangers of perchloric acid.
Oxidizing properties
KClO4 is an oxidizer in the sense that it exothermically transfers oxygen to combustible materials, greatly increasing their rate of combustion relative to that in air. Thus, with glucose it gives carbon dioxide:
3 KClO4 + C6H12O6 → 6 H2O + 6 CO2 + 3 KCl
The conversion of solid glucose into hot gaseous CO2 is the basis of the explosive force of this and other such mixtures. Even with cane sugar, KClO4 yields a low explosive, provided the necessary confinement. Otherwise such mixtures simply deflagrate with an intense purple flame characteristic of potassium. Flash compositions used in firecrackers usually consist of fine aluminium powder mixed with potassium perchlorate.
As an oxidizer, potassium perchlorate can be used safely in the presence of sulfur, whereas potassium chlorate cannot. The greater reactivity of chlorate is typical – perchlorates are kinetically poorer oxidants. Chlorate produces chloric acid, which is highly unstable and can lead to premature ignition of the composition. Correspondingly, perchloric acid is quite stable.[7]
In medicine
Potassium perchlorate can be used as an antithyroid agent used to treat hyperthyroidism, usually in combination with one other medication. This application exploits the similar ionic radii and hydrophilicity of perchlorate and iodide.
Other Uses
Since 2005, a cartridge with potassium perchlorate mixed with anthracene and sulfur is used for generating the black smoke signalling the failure of reaching a two-thirds majority needed for the election of new pope by a papal conclave.
↑Helmut Vogt, Jan Balej, John E. Bennett, Peter Wintzer, Saeed Akbar Sheikh, Patrizio Gallone "Chlorine Oxides and Chlorine Oxygen Acids" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a06_483
↑Greenwood, N. N.; Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.
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