Use
peroxomonosulphuric acid may be prepared by several methods depending on what form of the reagent is desired. Most commonly, it is made by treating potassium perfulfate (K2S2O8) with sulfuric acid. The dry form is prepared by slowly stirring 100 g K2S2O8 into 60 mL of concentrated H2SO4, followed by adding 300 g potassium sulfate. A liquid Caros acid is obtained by slowly stirring K2S2O8 into three times the mass of H2SO4. The dilute form of the reagent may be obtained by either mixing K2S2O8 to 40% H2SO4 or by treating K2S2O8 with H2SO4 and adding ice to the mixture.
Alternatively, peroxomonosulphuric acid may be prepared from hydrogen peroxide by treatment with either chlorosulfonic acid or with H2SO4 at 40C. A 90% H2O2 is used in the preparation.
peroxomonosulphuric acid is a strong oxidizing agent and is very unstable. All laboratory preparations must be carried out in an explosion-proof fume hood under temperature- controlled conditions and in the absence of impurities and oxidizable substances.