Potassium metabisulfite

Potassium metabisulfite, K2S2O5, also known as potassium pyrosulfite, is a white crystalline powder with a pungent odour. It is mainly used as an antioxidant or chemical sterilant. As a disulfite, it is chemically very similar to sodium metabisulfite, with which it is sometimes used interchangeably. Potassium metabisulfite has a monoclinic crystal structure.

Potassium metabisulfite
Names
Other names
Potassium pyrosulfite
Dipotassium disulfite
Potassium metabisulphite
Dipotassium disulphite
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.037.072
E number E224 (preservatives)
RTECS number
  • TT4920000
UNII
  • InChI=1S/2K.H2O5S2/c;;1-6(2)7(3,4)5/h;;(H,1,2)(H,3,4,5)/q2*+1;/p-2 Y
    Key: RWPGFSMJFRPDDP-UHFFFAOYSA-L Y
  • InChI=1/2K.H2O5S2/c;;1-6(2)7(3,4)5/h;;(H,1,2)(H,3,4,5)/q2*+1;/p-2
    Key: RWPGFSMJFRPDDP-NUQVWONBAF
  • [K+].[K+].[O-]S(=O)S([O-])(=O)=O
Properties
K2O5S2
Molar mass 222.31 g·mol−1
Appearance White crystalline powder
Odor Pungent (sulfur dioxide)
Density 2.34 g/cm3 (solid)
Melting point 190 °C (374 °F; 463 K) decomposes
450 g/L (20 °C)
Solubility Insoluble in ethanol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Irritant, asthma risk
GHS labelling:
Danger
H315, H318, H335
P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P310, P312, P321, P332+P313, P362, P403+P233, P405, P501
NFPA 704 (fire diamond)
1
0
0
Safety data sheet (SDS) ICSC 1175
Related compounds
Other anions
 Potassium bisulfite
Potassium sulfite
Other cations
 Sodium metabisulfite
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y verify (what is YN ?)
Infobox references
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