Potassium perchlorate

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Potassium perchlorate
Identifiers
CAS number7778-74-7 YesY
PubChem516900
ChemSpider22913 YesY
UNII42255P5X4D YesY
EC number231-912-9
UN number1489
ChEMBLCHEMBL1200696 N
RTECS numberSC9700000
Jmol-3D imagesImage 1
Properties
Molecular formulaKClO4
Molar mass138.55 g/mol
AppearanceColourless/white crystalline powder
Density2.5239 g/cm3
Melting point

525 °C

Boiling point

600 °C (decomp.)

Solubility in water0.75 g/100 mL (0 °C)
1.5 g/100 mL (25 °C)[1]
21.8 g/100 mL (100 °C)
Solubilitynegligible in alcohol
insoluble in ether
Refractive index (nD)1.4724
Structure
Crystal structurerhombohedral
Thermochemistry
Std enthalpy of
formation
ΔfHo298
−433 kJ·mol−1[2]
Standard molar
entropy
So298
151 J·mol−1·K−1[2]
Hazards
MSDSMSDS
EU Index017-008-00-5
EU classificationOxidant (O)
Harmful (Xn)
R-phrasesR9, R22
S-phrases(S2), S13, S22, S27
NFPA 704
NFPA 704.svg
0
1
1
OX
Related compounds
Other anionsPotassium chloride
Potassium chlorate
Potassium periodate
Other cationsAmmonium perchlorate
Sodium perchlorate
 N (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references
 
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Potassium perchlorate
Identifiers
CAS number7778-74-7 YesY
PubChem516900
ChemSpider22913 YesY
UNII42255P5X4D YesY
EC number231-912-9
UN number1489
ChEMBLCHEMBL1200696 N
RTECS numberSC9700000
Jmol-3D imagesImage 1
Properties
Molecular formulaKClO4
Molar mass138.55 g/mol
AppearanceColourless/white crystalline powder
Density2.5239 g/cm3
Melting point

525 °C

Boiling point

600 °C (decomp.)

Solubility in water0.75 g/100 mL (0 °C)
1.5 g/100 mL (25 °C)[1]
21.8 g/100 mL (100 °C)
Solubilitynegligible in alcohol
insoluble in ether
Refractive index (nD)1.4724
Structure
Crystal structurerhombohedral
Thermochemistry
Std enthalpy of
formation
ΔfHo298
−433 kJ·mol−1[2]
Standard molar
entropy
So298
151 J·mol−1·K−1[2]
Hazards
MSDSMSDS
EU Index017-008-00-5
EU classificationOxidant (O)
Harmful (Xn)
R-phrasesR9, R22
S-phrases(S2), S13, S22, S27
NFPA 704
NFPA 704.svg
0
1
1
OX
Related compounds
Other anionsPotassium chloride
Potassium chlorate
Potassium periodate
Other cationsAmmonium perchlorate
Sodium perchlorate
 N (verify) (what is: YesY/N?)
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 mL of water at 25 °C).[1]

Production[edit]

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).[3]

Oxidizing properties[edit]

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.[4]

In medicine[edit]

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[edit]

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.

References[edit]

  1. ^ a b "Potassium Perchlorate MSDS". J.T. Baker. 2007-02-16. Retrieved 2007-12-10. 
  2. ^ a b Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A22. ISBN 0-618-94690-X. 
  3. ^ 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
  4. ^ Greenwood, N. N.; Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.

External links[edit]