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Disulfuric acid



Disulfuric acid
IUPAC name Disulfuric acid
Other names Pyrosulfuric acid
Identifiers
CAS number 7783-05-3
SMILES OS(=O)(=O)OS(=O)(=O)O
Properties
Molecular formula H2S2O7
Molar mass 178.14168
Melting point

36°C

Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Disulfuric acid is a sulfur oxoacid. 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:

H2SO4 ⇌ H2O + SO3
SO3 + H2SO4 ⇌ H2S2O7

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

H2SO4 + SO3 → H2S2O7


Disulfuric acid is a strong acid and protonates 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 H20.(SO3)x e.g. H2S4O13(melting point 4°C).

See also

Footnotes

Greenwood, N. N.; Earnshaw, A. (1997). Chemistry of the Elements, 2nd Edition, Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4. 

 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Disulfuric_acid". A list of authors is available in Wikipedia.
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