Potassium metabisulfite

Potassium metabisulfite
Names



Other names Potassium pyrosulfite Dipotassium disulfite Potassium metabisulphite Dipotassium disulphite
Identifiers
CAS Number	16731-55-8^Y
3D model (JSmol)	Interactive image
ChemSpider	26061^Y
ECHA InfoCard	100.037.072
E number	E224 (preservatives)
PubChem CID	28019
RTECS number	TT4920000
UNII	65OE787Q7W^Y
CompTox Dashboard (EPA)	DTXSID1021293
InChI 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
SMILES [K+].[K+].[O-]S(=O)S([O-])(=O)=O
Properties
Chemical formula	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
Solubility in water	450 g/L (20 °C)
Solubility	Insoluble in ethanol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Irritant, asthma risk
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H315, H318, H335
Precautionary statements	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

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.^[1] 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.

YouTube Encyclopedic

1/3
Views:
16 658
30 518
20 932

Transcription

Preparation and reactions

Potassium metabisulfite can be prepared by treating a solution of potassium hydroxide with sulfur dioxide.^[2]

2 SO₂ + 2 KOH → K₂S₂O₅ + H₂O

It decomposes at 190 °C, yielding potassium sulfite and sulfur dioxide:

K₂S₂O₅ → K₂SO₃ + SO₂

Uses

It is used as a food additive, also known as E224.^[3] It is restricted in use and may cause allergic reactions in some sensitive persons.^[4]

Wine

Potassium metabisulfite is a common wine or must additive, in which it forms sulfur dioxide (SO₂). Sulfur dioxide is a disinfectant. It also acts as a potent antioxidant, protecting both the color and delicate flavors of wine.

A high dose would be 3 grams of potassium metabisulfite per six-gallon bucket of must (yielding roughly 75 ppm of SO₂) prior to fermentation; then 6 grams per six-gallon bucket (150 ppm of SO₂) at bottling. Some countries regulate the SO₂ content of wines.^[5]

Winemaking equipment is sanitized by spraying with a 1% SO₂ (2 tsp potassium metabisulfite per L) solution.

Beer

Potassium metabisulfite is sometimes used in the brewing industry to inhibit the growth of wild bacteria and fungi. This step is called 'stabilizing'. It is also used to neutralize monochloramine from tap water. It is used both by homebrewers and commercial brewers alike. It is not used as much for brewing beer, because the wort is almost always boiled, which kills most microorganisms.

Other uses

Potassium metabisulfite is sometimes added to lemon juice as a preservative.
Potassium metabisulfite is used in the textile industry for dyeing and cotton printing.
Potassium metabisulfite is sometimes used to precipitate gold from solution in aqua regia (as an alternative to sodium sulfite).
It is a component of certain photographic developers and solutions used in photographic processing, keeping active developing species from contact with oxygen.^[6]
It is used as a bleaching agent in the production of coconut cream.
It is used in some pickles as a preservative.
It is used in tint etching iron-based metal samples for microstructural analysis.^[7]
It is used in aam papad as a preservative.

References

^ Barberá, José Jiménez; Metzger, Adolf; Wolf, Manfred (2000). "Sulfites, Thiosulfates, and Dithionitesl Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a25_477. ISBN 978-3527306732.
^ Johnstone, H. F. (1946). "Sulfites and Pyrosulfites of the Alkali Metals". Inorganic Syntheses. Inorganic Syntheses. Vol. 2. pp. 162–167. doi:10.1002/9780470132333.ch49. ISBN 9780470132333.
^ List of E-number food additives
^ Metcalfe, Dean D.; Simon, Ronald A. (2003). Food allergy: adverse reactions to food and food additives. Malden, MA: Wiley-Blackwell. pp. 324–339. ISBN 978-0-632-04601-0.
^ Gorman-McAdams, Mary (July 9, 2020). "The Truth About Sulfites in Wine & the Myths of Red Wine Headaches". The Kitchn. Retrieved February 10, 2024.
^ "Potassium Metabisulfite".
^ "Color Metallography". 2011-05-04.

v t e Potassium compounds
H, (pseudo)halogens	KF KHF₂ KH KCl KClO KClO₃ KClO₄ KBr KBrO₃ KI KIO₃ KIO₄ KAt KCN KCNO KOCN KSCN
chalcogens	K₂O KOH K₂O₂ KO₂ KO₃ K₂S KHS K₂SO₃ KHSO₃ K₂SO₄ KHSO₄ KHSO₅ K₂S₂O₃ K₂S₂O₅ K₂S₂O₇ K₂S₂O₈ K₂Se K<sub>2</sub>SeO<sub>3</sub> K₂SeO₄ K₂Te K₂TeO₃ K<sub>2</sub>TeO<sub>4</sub> K₂Po
pnictogens	K₃N KNH₂ KN₃ KNO₂ KNO₃ K₃P KH₂PO₃ K₃PO₄ K₂HPO₄ KH₂PO₄ KPF₆ KAsO₂ K<sub>3</sub>AsO<sub>4</sub> K<sub>2</sub>HAsO<sub>4</sub> KH₂AsO₄
B, C group	B<sub>4</sub>K<sub>2</sub>O<sub>7</sub> K₂CO₃ KHCO₃ K₂SiO₃ K₂SiF₆ K₂Al₂O₄ K₂Al₂B₂O₇
trans metals	K₂PtCl₄ K₂Pt(CN)₄ K₂TiF₆ K₂PtCl₆ K₂ReCl₆ K₂ZrF₆ K₄Fe(CN)₆ K₃Fe(CN)₆ K₃Fe(C₂O₄)₃ K₂FeO₄ K₂MnO₄ KMnO₄ K₃CrO₄ K₂CrO₄ K₃CrO₈ KCrO₃Cl K₂Cr₂O₇ K<sub>2</sub>Cr<sub>3</sub>O<sub>10</sub> K<sub>2</sub>Cr<sub>4</sub>O<sub>13</sub> K₄Mo₂Cl₈
organic	KHCO₂ KCH₃CO₂ KCF₃CO₂ K₂C₂O₄ KHC₂O₄ KC₁₂H₂₃O₂ KC₁₈H₃₅O₂ C<sub>3</sub>H<sub>2</sub>K<sub>2</sub>O<sub>4</sub> C<sub>4</sub>H<sub>6</sub>KO<sub>4</sub> C<sub>5</sub>H<sub>7</sub>KO<sub>4</sub>

This page was last edited on 12 March 2024, at 21:31

From Wikipedia, the free encyclopedia