Sodium metabisulfite

Sodium metabisulfite or sodium pyrosulfite (IUPAC spelling; Br. E. sodium metabisulphite or sodium pyrosulphite) is an inorganic compound of chemical formula Na2S2O5. The substance is sometimes referred to as disodium metabisulfite. It is used as a disinfectant, antioxidant, and preservative agent. When dissolved in water it forms sodium bisulfite.

Sodium metabisulfite
Names
Other names
Sodium pyrosulfite
Sodium disulfite
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ECHA InfoCard 100.028.794
EC Number
  • 231-673-0
E number E223 (preservatives)
RTECS number
  • UX8225000
UNII
  • InChI=1S/2Na.H2O5S2/c;;1-6(2)7(3,4)5/h;;(H,1,2)(H,3,4,5)/q2*+1;/p-2
  • [O-]S(=O)S(=O)(=O)[O-].[Na+].[Na+]
Properties
Na2S2O5
Molar mass 190.107 g/mol
Appearance White to yellow powder
Odor Faint SO2
Density 1.48 g/cm3
Melting point 170 °C (338 °F; 443 K) decomposition begins at 150 °C
  • 45.1 g/100mL (0 °C)
  • 65.3 g/100mL (20 °C)
  • 81.7 g100 mL (100 °C)
Solubility Very soluble in glycerol
Slightly soluble in ethanol
Hazards
GHS labelling:
Danger
H302, H318
P264, P270, P280, P301+P312, P305+P351+P338, P310, P330, P501
NFPA 704 (fire diamond)
2
0
1
NIOSH (US health exposure limits):
PEL (Permissible)
None
REL (Recommended)
TWA 5 mg/m3
IDLH (Immediate danger)
N.D.
Safety data sheet (SDS) Mallinckrodt MSDS
Related compounds
Other anions
Sodium sulfite
Sodium bisulfite
Other cations
Potassium metabisulfite
Related compounds
Sodium dithionite
Sodium thiosulfate
Sodium sulfate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
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