Peroxydisulfuric acid

Peroxydisulfuric acid is an inorganic compound with a chemical formula (HO3SO)2. Also called Marshall's acid after Professor Hugh Marshall, who discovered it in 1891.[1]

Peroxydisulfuric acid
IUPAC names
peroxydisulfuric acid
Other names
Persulfuric acid, Peroxodisulfuric acid
3D model (JSmol)
  • InChI=1S/H2O8S2/c1-9(2,3)7-8-10(4,5)6/h(H,1,2,3)(H,4,5,6) Y
  • InChI=1/H2O8S2/c1-9(2,3)7-8-10(4,5)6/h(H,1,2,3)(H,4,5,6)/f/h1,4H
  • InChI=1/H2O8S2/c1-9(2,3)7-8-10(4,5)6/h(H,1,2,3)(H,4,5,6)
  • O=S(=O)(OOS(=O)(=O)O)O
Molar mass 194.13 g·mol−1
Appearance Colourless solid
Melting point 65 °C (149 °F; 338 K) (decomposes)
Conjugate base Peroxydisulfate
Related compounds
Other cations
Potassium persulfate
Sodium persulfate
Ammonium persulfate
Related compounds
Peroxymonosulfuric acid
Pyrosulfuric acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Structure and bonding

This oxoacid features sulfur in its +6 oxidation state and a peroxide group. Sulfur adopts the usual tetrahedral geometry.[2]


The acid is prepared by the reaction of chlorosulfuric acid with hydrogen peroxide:[3]

2ClSO3H + H2O2 → H2S2O8 + 2 HCl

Another method is the electrolysis of moderately concentrated sulfuric acid (60-70%) with platinum electrodes at high current density and voltage:

H2SO4 + H2O → H3O+ + HSO4 (dissociation of sulfuric acid)
2HSO4 → H2S2O8 + 2e (E0 = +2.4V) (bisulfate oxidation)
2H2SO4 → H2S2O8 + H2 (overall reaction)
3H2O → O3 + 6H+ (ozone produced as a side product)


Peroxydisulfuric acid is a precursor to several salts including sodium peroxydisulfate, potassium peroxydisulfate, and ammonium peroxydisulfate. These salts are used to initiate the polymerization of acrylonitrile, styrene, and related monomers. This application exploits the tendency of the peroxydisulfate anion to undergo homolysis to produce radicals. They are also used as cleaning of circuit boards.[3]

See also


  1. Senning, Alexander (2006-10-30). Elsevier's Dictionary of Chemoetymology: The Whys and Whences of Chemical Nomenclature and Terminology. ISBN 9780080488813.
  2. Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
  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.{{cite encyclopedia}}: CS1 maint: multiple names: authors list (link)

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