H2S2O8 - Peroxydisulfuric Acid

What is Peroxydisulfuric Acid?

Peroxydisulfuric Acid is a colorless solid and one of the most powerful peroxyacid oxidants available. Peroxydisulfuric Acid is an inorganic compound with the chemical formula H2S2O8. It can be generated from potassium or ammonium persulfate in acidic solution. It is an anhydride of sulfuric and peroxydisulfuric acid and may be prepared by oxidation of oleum with ozone or hydrogen peroxide. Also called Marshall’s acid, peroxydisulfuric acid can be produced by electrolyzing an aqueous solution containing sulfate ions in an electrolysis reactor should be produced by electrolyzing.

Other names – persulfuric acid, sulfo oxy hydrogen sulfate


Peroxydisulfuric Acid



Molecular Weight/ Molar Mass

194.14 g/mol

Conjugate base‎


Melting Point

65 °C

Chemical Formula


Peroxydisulfuric Acid Structure – H2S2O8

Peroxydisulfuric Acid Structure

Physical Properties of Peroxydisulfuric Acid – H2S2O8




Colourless solid

Covalently-Bonded Unit


Heavy Atom Count


Hydrogen Bond Acceptor



Soluble in water

Chemical Properties of Peroxydisulfuric Acid – H2S2O8

  • Peroxydisulfuric Acid dissolves in water forms hydrogen peroxide and sulfuric acid. The chemical equation is given below.
  • H2S2O8 + 2H2O → H2O2 + 2H2SO4

  • Peroxydisulfuric Acid reacts with silver nitrate in aqueous medium forms silver oxide, sulfuric acid and nitric acid.
  • H2S2O8 + 2AgNO3 + 2H2O → Ag2O2 + 2H2SO4 + 2HNO3

Uses of Peroxydisulfuric Acid – H2S2O8

  • Use of peroxydisulfuric acid and its salts as a source of hydrogen peroxide opened the way for large-scale production of sulfuric acid.
  • Used as a hypo eliminator in photography.
  • Used as a strong oxidant but the quantity of the oxidizing agent used can be varied in accordance to the desired reaction rate.

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