Potassium pyrosulfate

Potassium pyrosulfate
Names
	IUPAC name dipotassium (sulfonatooxy)sulfonate
	Other names Potassium pyrosulphate; potassium disulfate
Identifiers
CAS Number	7790-62-7 ;
3D model (JSmol)	Interactive image;
ChemSpider	56432 ;
ECHA InfoCard	100.029.288
EC Number	232-216-8;
PubChem CID	62681;
UNII	AVJ6ZST7L6;
CompTox Dashboard (EPA)	DTXSID10889580 ;
	InChI InChI=1S/2K.H2O7S2/c;;1-8(2,3)7-9(4,5)6/h;;(H,1,2,3)(H,4,5,6)/q2+1;/p-2 Key: KAQHZJVQFBJKCK-UHFFFAOYSA-L ; InChI=1/2K.H2O7S2/c;;1-8(2,3)7-9(4,5)6/h;;(H,1,2,3)(H,4,5,6)/q2+1;/p-2 Key: KAQHZJVQFBJKCK-NUQVWONBAQ;
	SMILES [O-]S(=O)(=O)OS(=O)(=O)[O-].[K+].[K+];
Properties
Chemical formula	K2O7S2
Molar mass	254.31 g·mol−1
Density	2.28 g/cm3
Melting point	325 °C (617 °F; 598 K)
Solubility in water	25.4 g/100 mL (20 °C)
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H314, H331
Precautionary statements	P260, P261, P264, P271, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P311, P321, P363, P403+P233, P405, P501
	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

Potassium pyrosulfate, or potassium disulfate, is an inorganic compound with the chemical formula K₂S₂O₇.

Production

Potassium pyrosulfate is obtained by the thermal decomposition of other salts, most directly from potassium bisulfate:^[1]

2 KHSO₄ → K₂S₂O₇ + H₂O

Temperatures above 600°C further decompose potassium pyrosulfate to potassium sulfate and sulfur trioxide however:^[2]

K₂S₂O₇ → K₂SO₄ + SO₃

Other salts, such as potassium trisulfate,^[3] can also decompose into potassium pyrosulfate.

Potassium pyrosulfate contains the pyrosulfate anion which has a dichromate-like structure. The geometry can be visualized as a tetrahedron with two corners sharing the SO₄ anion's configuration and a centrally bridged oxygen atom.^[4] A semi-structural formula for the pyrosulfate anion is O₃SOSO₃²⁻. The oxidation state of sulfur in this compound is +6.

Potassium pyrosulfate is used in analytical chemistry; samples are fused with potassium pyrosulfate, (or a mixture of potassium pyrosulfate and potassium fluoride) to ensure complete dissolution prior to a quantitative analysis.^[5]^[6]

The compound is also present in a catalyst in conjunction with vanadium(V) oxide in the industrial production of sulfur trioxide.^[7]

Names

IUPAC name dipotassium (sulfonatooxy)sulfonate
Other names Potassium pyrosulphate; potassium disulfate
Identifiers
CAS Number	7790-62-7^Y
3D model (JSmol)	Interactive image
ChemSpider	56432^Y
ECHA InfoCard	100.029.288
EC Number	232-216-8
PubChem CID	62681
UNII	AVJ6ZST7L6
CompTox Dashboard (EPA)	DTXSID10889580
InChI InChI=1S/2K.H2O7S2/c;;1-8(2,3)7-9(4,5)6/h;;(H,1,2,3)(H,4,5,6)/q2+1;/p-2^N Key: KAQHZJVQFBJKCK-UHFFFAOYSA-L^N InChI=1/2K.H2O7S2/c;;1-8(2,3)7-9(4,5)6/h;;(H,1,2,3)(H,4,5,6)/q2+1;/p-2 Key: KAQHZJVQFBJKCK-NUQVWONBAQ
SMILES [O-]S(=O)(=O)OS(=O)(=O)[O-].[K+].[K+]
Properties
Chemical formula	K₂O₇S₂
Molar mass	254.31 g·mol⁻¹
Density	2.28 g/cm³
Melting point	325 °C (617 °F; 598 K)
Solubility in water	25.4 g/100 mL (20 °C)
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H314, H331
Precautionary statements	P260, P261, P264, P271, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P311, P321, P363, P403+P233, P405, P501
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