Disulfuric acid
Encyclopedia
Disulfuric acid is an oxoacid
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:
The acid is prepared by reacting excess SO3 with sulfuric acid:
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 pyrosulfate
s, e.g. potassium pyrosulfate
.
There are other related acids with the general formula H2O.(SO3)x though none are isolable.
Oxoacid
An oxoacid is an acid that contains oxygen. To be more specific, it is an acid that:#contains oxygen#contains at least one other element#has at least one hydrogen atom bound to oxygen#forms an ion by the loss of one or more protons....
of sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
. It is a major constituent of fuming sulfuric acid, oleum
Oleum
Oleum , or fuming sulfuric acid refers to a solution of various compositions of sulfur trioxide in sulfuric acid or sometimes more specifically to disulfuric acid ....
, and this is how most chemists encounter it. It is also a minor constituent of liquid anhydrous sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
due to the equilibria:
- 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 pyrosulfate
Pyrosulfate
In chemistry, disulfate or pyrosulfate is the anion with the molecular formula [S2O7]2−. Disulfate is the IUPAC name. It has a dichromate like structure and can be visualised as two corner sharing SO4 tetrahedra, with a bridging oxygen atom....
s, e.g. potassium pyrosulfate
Potassium pyrosulfate
Potassium pyrosulfate is a chemical compound, K2S2O7. It contains the pyrosulfate anion S2O72− which has a dichromate like structure and can be visualised as two corner sharing SO4 tetrahedra, with a bridging oxygen atom. A semi-structural formula for pyrosulfate ion is O3SOSO32−...
.
There are other related acids with the general formula H2O.(SO3)x though none are isolable.