Sodium pyrosulfate

Sodium pyrosulfate is an inorganic compound with the chemical formula of Na₂S₂O₇.^[1] It is a colorless salt.^[3] It hydrolyses in water to form sodium bisulfate with a chemical formula of NaHSO4 which has a pH of around 1.

Sodium pyrosulfate^[1]

Names
IUPAC name Disodium disulfate
Other names Sodium pyrosulphate; Disulfuric acid disodium salt, disodium disulfate; Sodium metabisulfate
Identifiers
CAS Number	13870-29-6 Y
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL111016 Y
ChemSpider	7970254
ECHA InfoCard	100.034.190
EC Number	237-625-5
PubChem CID	9794487
CompTox Dashboard (EPA)	DTXSID60889631
InChI InChI=1S/2Na.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: JXAZAUKOWVKTLO-UHFFFAOYSA-L
SMILES [Na+].[Na+].[O-]S(=O)(=O)OS(=O)(=O)[O-]
Properties
Chemical formula	Na2S2O7
Molar mass	222.12 g/mol
Appearance	Translucent white crystals
Density	2.658 g/cm3
Melting point	400.9 °C (753.6 °F; 674.0 K)
Boiling point	decomposes at 460 °C (860 °F; 733 K)
Solubility in water	hydrolyses[2]
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

Preparation

Sodium pyrosulfate is obtained by heating sodium bisulfate to 280 °C (536 °F) ^[4][5]

2 NaHSO₄ → Na₂S₂O₇ + H₂O

Temperatures above 460 °C further decompose the compound, producing sodium sulfate and sulfur trioxide:

Na₂S₂O₇ → Na₂SO₄ + SO₃

Applications

Sodium pyrosulfate was used in analytical chemistry. Samples are fused with sodium pyrosulfate to ensure complete dissolution before a quantitative analysis.^[6][7]

See also

• Pyrosulfate
• Potassium bisulfate
• Potassium pyrosulfate