Disulfuric acid

Disulfuric acid
Ball and stick model of the disulfuric acid molecule
Names
IUPAC name
Disulfuric acid
Other names
Pyrosulfuric acid, Oleum
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.029.069 Edit this at Wikidata
EC Number
  • 231-976-8
MeSH Pyrosulfuric+acid
UNII
  • InChI=1S/H2O7S2/c1-8(2,3)7-9(4,5)6/h(H,1,2,3)(H,4,5,6) checkY
    Key: VFNGKCDDZUSWLR-UHFFFAOYSA-N checkY
  • InChI=1/H2O7S2/c1-8(2,3)7-9(4,5)6/h(H,1,2,3)(H,4,5,6)
    Key: VFNGKCDDZUSWLR-UHFFFAOYAZ
  • OS(=O)(=O)OS(O)(=O)=O
  • OS(=O)(=O)OS(=O)(=O)O
  • O=S(=O)(O)OS(=O)(=O)O
Properties
H2O7S2
Molar mass 178.13 g·mol−1
Appearance colorless
Melting point 36 °C (97 °F; 309 K)
Conjugate base Disulfate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)
Infobox references

Disulfuric acid (alternative spelling disulphuric acid) or pyrosulfuric acid (alternative spelling pyrosulphuric acid), also named oleum, is a sulfur oxoacid. It is a major constituent of fuming sulfuric acid, oleum, and this is how most chemists encounter it. As confirmed by X-ray crystallography, the molecule consists of a pair of SO2(OH) groups joined by an oxide.

Reactions

It is also a minor constituent of liquid anhydrous sulfuric acid due to the equilibria:

The acid is prepared by reacting excess sulfur trioxide (SO3) with sulfuric acid:

Disulfuric acid can be seen as the sulfuric acid analog 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.

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

See also


This page was last updated at 2024-01-21 12:02 UTC. Update now. View original page.

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