Potassium perchlorate

Potassium perchlorate

Names
Other names Potassium chlorate(VII); Perchloric acid, potassium salt; peroidin
Identifiers
CAS Number	7778-74-7
ChEMBL	ChEMBL1200696
ChemSpider	22913
EC Number	231-912-9
Jmol 3D model	Interactive image
PubChem	516900
RTECS number	SC9700000
UNII	42255P5X4D
UN number	1489
InChI InChI=1S/ClHO4.K/c2-1(3,4)5;/h(H,2,3,4,5);/q;+1/p-1 Key: YLMGFJXSLBMXHK-UHFFFAOYSA-M InChI=1/ClHO4.K/c2-1(3,4)5;/h(H,2,3,4,5);/q;+1/p-1 Key: YLMGFJXSLBMXHK-REWHXWOFAB
SMILES [K+].[O-]Cl(=O)(=O)=O
Properties
Chemical formula	ClKO4
Molar mass	138.54 g·mol^−1
Appearance	colourless/ white crystalline powder
Density	2.5239 g/cm^3
Melting point	610 °C (1,130 °F; 883 K) decomposes from 400 °C[1][2]
Solubility in water	0.76 g/100 mL (0 °C) 1.5 g/100 mL (25 °C)[3] 4.76 g/100 mL (40 °C) 21.08 g/100 mL (100 °C)[4]
Solubility product (Ksp)	1.05·10^−2[5]
Solubility	negligible in alcohol insoluble in ether
Solubility in ethanol	47 mg/kg (0 °C) 120 mg/kg (25 °C)[4]
Solubility in acetone	1.6 g/kg[4]
Solubility in ethyl acetate	15 mg/kg[4]
Refractive index (nD)	1.4724
Structure
Crystal structure	Rhombohedral
Thermochemistry
Specific heat capacity (C)	111.35 J/mol·K[6]
Std molar entropy (S^o298)	150.86 J/mol·K[6]
Std enthalpy of formation (ΔfH^o298)	-433 kJ/mol[7]
Gibbs free energy (ΔfG˚)	-300.4 kJ/mol[4]
Hazards
Safety data sheet	MSDS
GHS pictograms	[2]
GHS signal word	Danger
GHS hazard statements	H271, H302[2]
GHS precautionary statements	P220[2]
EU classification (DSD)	O Xn
R-phrases	R9, R22
S-phrases	(S2), S13, S22, S27
NFPA 704	0 1 1 OX
Related compounds
Other anions	Potassium chloride Potassium chlorate Potassium periodate
Other cations	Ammonium perchlorate Sodium perchlorate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Potassium perchlorate is the inorganic salt with the chemical formula KClO₄. Like other perchlorates, this salt is a strong 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 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 It has been used as a solid rocket propellant, although in that application it has mostly been replaced by the higher performance ammonium perchlorate.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).^[3]

Production

Potassium perchlorate in crystal form

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).^[8] 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 a mixture of aluminium powder and potassium perchlorate. This mixture, sometimes called flash powder, is also used in ground and air fireworks.

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.^[9]

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 a new pope by a papal conclave.

References

1. Benenson, Walter; Stöcker, Horst. Handbook of Physics. Springer. p. 780. ISBN 0387952691.
2. Sigma-Aldrich Co., Potassium perchlorate. Retrieved on 2014-05-27.
3. "Potassium Perchlorate MSDS". J.T. Baker. 2007-02-16. Retrieved 2007-12-10.
4. http://chemister.ru/Database/properties-en.php?dbid=1&id=519
5. http://www.solubilityofthings.com/water/ions_solubility/ksp_chart.php
6. Potassium perchlorate in Linstrom, P.J.; Mallard, W.G. (eds.) NIST Chemistry WebBook, NIST Standard Reference Database Number 69. National Institute of Standards and Technology, Gaithersburg MD. http://webbook.nist.gov (retrieved 2014-05-27)
7. Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A22. ISBN 0-618-94690-X.
8. 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
9. Greenwood, N. N.; Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.

External links

• WebBook page for KClO₄

Salts and the ester of the perchlorate ion
HClO4																	He
LiClO4	Be(ClO4)2											B(ClO4)4^−	ROClO3	N(ClO4)3 NH4ClO4	O	FClO4	Ne
NaClO4	Mg(ClO4)2											Al(ClO4)3	Si	P	S	ClO4^− ClOClO3 Cl2O7	Ar
KClO4	Ca(ClO4)2	Sc(ClO4)3	Ti(ClO4)4	VO(ClO4)3	Cr(ClO4)3	Mn(ClO4)2	Fe(ClO4)3	Co(ClO4)2, Co(ClO4)3	Ni(ClO4)2	Cu(ClO4)2	Zn(ClO4)2	Ga(ClO4)3	Ge	As	Se	Br	Kr
RbClO4	Sr(ClO4)2	Y	Zr	Nb	Mo	Tc	Ru	Rh	Pd(ClO4)2	AgClO4	Cd(ClO4)2	In	Sn	Sb	Te	I	Xe
CsClO4	Ba(ClO4)2		Hf	Ta	W	Re	Os	Ir	Pt	Au	Hg2(ClO4)2, Hg(ClO4)2	Tl(ClO4)3	Pb(ClO4)2	Bi(ClO4)3	Po	At	Rn
Fr	Ra		Rf	Db	Sg	Bh	Hs	Mt	Ds	Rg	Cn	Uut	Fl	Uup	Lv	Uus	Uuo
		↓
		La	Ce(ClO4)x	Pr	Nd	Pm	Sm	Eu	Gd	Tb	Dy	Ho	Er	Tm	Yb	Lu
		Ac	Th	Pa	UO2(ClO4)2	Np	Pu	Am	Cm	Bk	Cf	Es	Fm	Md	No	Lr