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Potassium perchlorate
Potassium perchlorate.png
Other names Potassium chlorate(VII)
Perchloric acid, potassium salt
CAS number 7778-74-7 Yes check.svgY
PubChem 516900
EC number 231-912-9
UN number 1489
RTECS number SC9700000
Molecular formula KClO4
Molar mass 138.55 g/mol
Appearance Colourless/white crystalline powder
Density 2.5239 g/cm3
Melting point

525 °C

Boiling point

600 °C (decomp.)

Solubility in water 0.75 g/100 mL (0 °C)
1.5 g/100 mL (25 °C)[1]
21.8 g/100 mL (100 °C)
Solubility negligible in alcohol
insoluble in ether
Crystal structure rhombohedral
EU Index 017-008-00-5
EU classification Oxidant (O)
Harmful (Xn)
R-phrases R9, R22
S-phrases (S2), S13, S22, S27
NFPA 704
NFPA 704.svg
Related compounds
Other anions Potassium chloride
Potassium chlorate
Potassium periodate
Other cations Ammonium perchlorate
Sodium perchlorate
 Yes check.svgY (what is this?)  (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Potassium perchlorate is the inorganic salt with the chemical formula KClO4. Like other perchlorates, this salt is a strong oxidizer and potentially reacts with many organic substances. This usually obtained as a colorless, crystalline solid is a common oxidizer 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 It has been used as a solid rocket propellant, although in that application it has mostly been replaced by the higher performance ammonium perchlorate. KClO4 has the lowest solubility of the alkali metal perchlorates (1.5 g in 100 g of water at 25 °C).[1]



KClO4 is prepared industrially by treating an aqueous solution of sodium perchlorate with KCl. This ion exchange process exploits the low solubility of KClO4, which is about 100x less than the solubility NaClO4 (209.6 g/100 mL at 25 °C).[2]

Oxidizing properties

KClO4 is an oxidizer in the sense that it exothermically transfers oxygen to organic compounds. 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 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 whereas chloric acid is not.[3]

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.


  1. ^ a b "Potassium Perchlorate MSDS". J.T. Baker. 2007-02-16. Retrieved 2007-12-10.  
  2. ^ 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. doi:10.1002/14356007.a06_483
  3. ^ Greenwood, N. N.; Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.

External links

Simple English

File:Perclorato de Potá
A crystal of potassium perchlorate

Potassium perchlorate is a chemical compound. Its chemical formula is KClO4. It contains potassium and perchlorate ions.



Potassium perchlorate is a colorless crystalline solid. It dissolves in water only a little. It is an oxidizing agent. It can react with glucose to make carbon dioxide, potassium chloride, and water. It can be mixed with sulfur, while potassium chlorate cannot safely be mixed.


It is made by reacting potassium chloride with sodium perchlorate. This makes the potassium perchlorate crystals.


It is used as a rocket propellant. It can also be used in fireworks and other explosives. Ammonium perchlorate is used more, though.

See also

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