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Potassium persulfate

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Potassium persulfate
Two potassium cations and one peroxydisulfate anion
Two potassium cations and one peroxydisulfate anion
Ball-and-stick model of the crystal structure
Ball-and-stick model of the crystal structure
Potassium persulfate as a white powder
Potassium persulfate as a white powder
Names
Other names
potassium peroxydisulfate
Anthion
potassium perdisulfate
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.028.893 Edit this at Wikidata
EC Number
  • 231-781-8
E number E922 (glazing agents, ...)
RTECS number
  • SE0400000
UN number 1492
  • InChI=1S/2K.H2O8S2/c;;1-9(2,3)7-8-10(4,5)6/h;;(H,1,2,3)(H,4,5,6)/q2*+1;/p-2 ☒N
    Key: USHAGKDGDHPEEY-UHFFFAOYSA-L ☒N
  • InChI=1/2K.H2O8S2/c;;1-9(2,3)7-8-10(4,5)6/h;;(H,1,2,3)(H,4,5,6)/q2*+1;/p-2
    Key: USHAGKDGDHPEEY-NUQVWONBAA
  • [O-]S(=O)(=O)OOS(=O)(=O)[O-].[K+].[K+]
Properties
K2S2O8
Molar mass 270.322 g/mol
Appearance white powder
Odor odorless
Density 2.477 g/cm3[1]
Melting point < 100 °C (212 °F; 373 K) (decomposes)
1.75 g/100 mL (0 °C)
4.49 g/100 ml (20 °C)
Solubility insoluble in alcohol
1.467
Structure
triclinic
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 0: Will not burn. E.g. waterInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazard OX: Oxidizer. E.g. potassium perchlorate
2
0
1
OX
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
802 mg/kg (oral, rat)[2]
Safety data sheet (SDS) ICSC 1133
Related compounds
Other anions
 Potassium sulfite
Potassium sulfate
Potassium peroxymonosulfate
Other cations
 Sodium persulfate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)
Not to be confused with potassium peroxymonosulfate.

Potassium persulfate is the inorganic compound with the formula K2S2O8. Also known as potassium peroxydisulfate or KPS, it is a white solid that is highly soluble in water. This salt is a powerful oxidant, commonly used to initiate polymerizations.

Preparation

Potassium persulfate can be prepared by electrolysis of a cold solution potassium bisulfate in sulfuric acid at a high current density.[1]

2 KHSO4 → K2S2O8 + H2

It can also be prepared by adding potassium bisulfate (KHSO4) to a solution of the more soluble salt ammonium peroxydisulfate (NH4)2S2O8. In principle it can be prepared by chemical oxidation of potassium sulfate using fluorine.

Uses

This salt is used to initiate polymerziation of various alkenes leading to commercially important polymers such as styrene-butadiene rubber and polytetrafluoroethylene and related materials. In solution, the dianion dissociates to give radicals:[3]

[O3SO-OSO3]2− 2 [SO4]−

It is used in organic chemistry as an oxidizing agent,[4] for instance in the Elbs persulfate oxidation of phenols.

As a strong bleaching agent, it is used in hair dye substances as whitening agent with hydrogen peroxide.

As a strong oxidant of environmental samples, mainly aqueous, for the determination of the total nitrogenous compounds therein. [5]

It is a food additive[citation needed].

Precautions

The salt is a strong oxidant and is incompatible with organic compounds.

References

  1. ^ a b F. Feher, "Potassium Peroxydisulfate" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 392.
  2. ^ http://chem.sis.nlm.nih.gov/chemidplus/rn/7727-21-1
  3. ^ Harald Jakob, Stefan Leininger, Thomas Lehmann, Sylvia Jacobi, Sven Gutewort. "Peroxo Compounds, Inorganic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_177.pub2. ISBN 978-3-527-30673-2.{{cite encyclopedia}}: CS1 maint: multiple names: authors list (link)
  4. ^ Encyclopedia of Reagents for Organic Synthesis, vol. 1, pp 193-197(1995)
  5. ^ Method 4500-N C. Persulfate Method for Total Nitrogen. In Standard Methods for the Examination of Water and Wastewater
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