Kalpana Kalpana (Editor)

Disulfuric acid

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Formula
  
H2S2O7

Disulfuric acid httpsuploadwikimediaorgwikipediacommonsthu

Disulfuric acid (alternative spelling disulphuric acid) or pyrosulfuric acid (alternative spelling pyrosulphuric acid), also named oleum is an oxyacid of sulfur. It is a major constituent of fuming sulfuric acid, oleum and this is how most chemists encounter it. It is also a minor constituent of liquid anhydrous sulfuric acid due to the equilibria:

Disulfuric acid Sulfur oxoacid Wikipedia
H2SO4 ⇌ H2O + SO3 SO3 + H2SO4 ⇌ H2S2O7

The acid is prepared by reacting excess SO3 with sulfuric acid:

H2SO4 + SO3 → H2S2O7

Disulfuric acid can be seen as the sulfuric acid analogue of an acid anhydride. The mutual electron-withdrawing effects of each sulfuric acid unit on its neighbour causes a marked increase in acidity. Disulfuric acid is strong enough to protonate "normal" sulfuric acid in the (anhydrous) sulfuric acid solvent system. There are salts of disulfuric acid, commonly called pyrosulfates, e.g. potassium pyrosulfate.

Disulfuric acid FileDischwefelsure Disulfuric acidsvg Wikimedia Commons

There are other related acids with the general formula H2O·(SO3)x though none are isolable.

Disulfuric acid Disulfuric acid Wikipedia

Disulfuric acid Disulfuric acid Wikipedia

Disulfuric acid Disulfuric acid monohydrate H2O7S2H2O

Disulfuric acid Disulfuric acid Wikiwand

Disulfuric acid Disulfuric acid H2O7S2 ChemSpider

References

Disulfuric acid Wikipedia