Potassium persulfate

Potassium persulfate
Other names potassium peroxydisulfate Anthion potassium perdisulfate
Identifiers
CAS number	7727-21-1 Y
PubChem	24412
EC number	231-781-8
UN number	1492
RTECS number	SE0400000
Properties
Molecular formula	K2S2O8
Molar mass	270.322 g/mol
Appearance	white powder
Density	2.477 g/cm3 [1]
Melting point	<100 °C decomp.
Solubility in water	1.75 g/100 mL (0 °C) 5.29 g/100 ml (20 °C)
Hazards
MSDS	ICSC 1133
EU Index	016-061-00-1
EU classification	Oxidant (O) Harmful (Xn) Irritant (Xi)
R-phrases	R8, R22, R36/37/38, R42/43
S-phrases	(S2), S22, S24, S26, S37
NFPA 704	0 2 1 OX
Flash point	Non-flammable
Related compounds
Other anions	Potassium sulfite Potassium sulfate Potassium peroxymonosulfate
Other cations	Sodium persulfate
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Not to be confused with potassium peroxymonosulfate.

Potassium persulfate (K₂S₂O₈) (also potassium peroxydisulfate or KPS) is a compound.

Contents 1 Uses 2 Preparation 3 Precautions 4 References

Uses

It is a food additive and it is used in organic chemistry as an oxidizing agent for instance in the Elbs persulfate oxidation, and in hair dye substances as whitening agent with hydrogen peroxide. It takes also an important role as initiator for emulsion polymerization.

For a review of its uses in organic chemistry, see Encyclopedia of Reagents for Organic Synthesis, vol. 1, pp 193-197(1995).

Preparation

Potassium persulfate can be prepared by electrolysis of a mixture between potassium sulfate and hydrogen sulfate at a high current density.

2 KHSO₄ → K₂S₂O₈ + H₂

It can also be prepared by adding potassium bisulfate (KHSO₄) to an electrolyzed solution of ammonium bisulfate (NH₄HSO₄).

Another reaction of its formation is the following (although the practical use of it outside of clandestine chemistry is doubtable).

I₂ + 2KHSO₄ → K₂S₂O₆(O₂) + 2HI

Precautions

Conditions/substances to avoid are: heat, flames, ignition sources, powdered metals, phosphorus, hydrides, organic matter, halogens, acids and alkalis.

References

Potassium compounds KBr KBrO3 KCN KCNO KCl KClO3 KClO4 KF KH KHCO2 KHCO3 KHF2 KHSO3 KHSO4 KH2AsO4 KI KIO3 KIO4 KMnO4 KN3 KNO2 KNO3 KOCN KOH KO2 KPF6 KSCN K2CO3 K2CrO4 K2Cr2O7 K2FeO4 K2MnO4 K2O K2O2 K2PtCl4 K2PtCl6 K2S K2SO3 K2SO4 K2SO5 K2S2O5 K2S2O7 K2S2O8 K2SiO3 K3[Fe(CN)6] K3[Fe(C2O4)3] K4[Fe(CN)6] K3PO4 K4MnO4 K4Mo2Cl8

E numbers Colours (E100–199) • Preservatives (E200–299) • Antioxidants & acidity regulators (E300–399) • Thickeners, stabilisers & emulsifiers (E400–499) • pH regulators & anticaking agents (E500–599) • Flavour enhancers (E600–699) • Miscellaneous (E900–999) • Additional chemicals (E1100–1599) Waxes (E900–909) • Synthetic glazes (E910–919) • Improving agents (E920–929) • Packaging gases (E930–949) • Sweeteners (E950–969) • Foaming agents (E990–999) L-cysteine (E920) • L-cystine (E921) • Potassium persulfate (E922) • Ammonium persulfate (E923) • Potassium bromate (E924) • Chlorine (E925) • Chlorine dioxide (E926) • Azodicarbonamide (E927) • Carbamide (E927b) • Benzoyl peroxide (E928)