Disulfuric acid

Disulfuric acid
Names
	IUPAC name Disulfuric acid
	Other names Pyrosulfuric acid, Oleum
Identifiers
CAS Number	7783-05-3 ;
3D model (JSmol)	Interactive image; Interactive image; Interactive image;
ChEBI	CHEBI:29211 ;
ChemSpider	56433 ;
ECHA InfoCard	100.029.069
EC Number	231-976-8;
MeSH	Pyrosulfuric+acid
PubChem CID	62682;
UNII	NTC1O8E83E ;
CompTox Dashboard (EPA)	DTXSID7064817 ;
	InChI InChI=1S/H2O7S2/c1-8(2,3)7-9(4,5)6/h(H,1,2,3)(H,4,5,6) Key: VFNGKCDDZUSWLR-UHFFFAOYSA-N ; InChI=1/H2O7S2/c1-8(2,3)7-9(4,5)6/h(H,1,2,3)(H,4,5,6) Key: VFNGKCDDZUSWLR-UHFFFAOYAZ;
	SMILES OS(=O)(=O)OS(O)(=O)=O; OS(=O)(=O)OS(=O)(=O)O; O=S(=O)(O)OS(=O)(=O)O;
Properties
Chemical formula	H2O7S2
Molar mass	178.13 g·mol−1
Appearance	colorless
Melting point	36 °C (97 °F; 309 K)
Acidity (pKa)	2.5 (20 °C; in conc. H2SO4)
Conjugate base	Disulfate
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Disulfuric acid (alternative spelling disulphuric acid) or pyrosulfuric acid (alternative spelling pyrosulphuric acid), also named oleum, is a sulfur oxoacid.^[3] 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.^[4]

^ International Union of Pure and Applied Chemistry (2005). Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005). Cambridge (UK): RSC–IUPAC. ISBN 0-85404-438-8. p. 130. Electronic version.
^ Perrin, D. D., ed. (1982) [1969]. Ionisation Constants of Inorganic Acids and Bases in Aqueous Solution. IUPAC Chemical Data (2nd ed.). Oxford: Pergamon (published 1984). Entry 62. ISBN 0-08-029214-3. LCCN 82-16524.
^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
^ Hönle, Wolfgang (1991). "Crystal structure of H2S2O7 at 298 K". Zeitschrift für Kristallographie - Crystalline Materials. 196 (1–4). doi:10.1524/zkri.1991.196.14.279. S2CID 101311329.

[1] International Union of Pure and Applied Chemistry (2005). Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005). Cambridge (UK): RSC–IUPAC. ISBN 0-85404-438-8. p. 130. Electronic version.

[P82db-2] Perrin, D. D., ed. (1982) [1969]. Ionisation Constants of Inorganic Acids and Bases in Aqueous Solution. IUPAC Chemical Data (2nd ed.). Oxford: Pergamon (published 1984). Entry 62. ISBN 0-08-029214-3. LCCN 82-16524.

[3] Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.

[4] Hönle, Wolfgang (1991). "Crystal structure of H2S2O7 at 298 K". Zeitschrift für Kristallographie - Crystalline Materials. 196 (1–4). doi:10.1524/zkri.1991.196.14.279. S2CID 101311329.

[1]

[2]

[3]

[4]

Names


IUPAC name Disulfuric acid ^[1]
Other names Pyrosulfuric acid, Oleum
Identifiers
CAS Number	7783-05-3^Y
3D model (JSmol)	Interactive image Interactive image Interactive image
ChEBI	CHEBI:29211^Y
ChemSpider	56433^Y
ECHA InfoCard	100.029.069
EC Number	231-976-8
MeSH	Pyrosulfuric+acid
PubChem CID	62682
UNII	NTC1O8E83E^N
CompTox Dashboard (EPA)	DTXSID7064817
InChI InChI=1S/H2O7S2/c1-8(2,3)7-9(4,5)6/h(H,1,2,3)(H,4,5,6)^Y Key: VFNGKCDDZUSWLR-UHFFFAOYSA-N^Y InChI=1/H2O7S2/c1-8(2,3)7-9(4,5)6/h(H,1,2,3)(H,4,5,6) Key: VFNGKCDDZUSWLR-UHFFFAOYAZ
SMILES OS(=O)(=O)OS(O)(=O)=O OS(=O)(=O)OS(=O)(=O)O O=S(=O)(O)OS(=O)(=O)O
Properties
Chemical formula	H₂O₇S₂
Molar mass	178.13 g·mol⁻¹
Appearance	colorless
Melting point	36 °C (97 °F; 309 K)
Acidity (pK_a)	2.5 (20 °C; in conc. H₂SO₄)^[2]
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 ^YN ?) Infobox references