Sodium metabisulfite

Sodium metabisulfite

Chembox new
Name = Sodium Metabisulfite
ImageFile = Sodium metabisulfite.jpg
ImageName = Sodium metabisulfite
OtherNames = Sodium Pyrosulfite
Sodium Disulfite
Section1 = Chembox Identifiers
CASNo = 7681-57-4

Section2 = Chembox Properties
Formula = Na2S2O5
MolarMass = 190.1 g/mol
Appearance = white powder
Density = 1100 to 1200 kg/m³ (solid)
Solubility = 65 (25 °C)
Solubility = 47 (20 °C)
MeltingPt = >170 °C (begins at 150)
BoilingPt =

Section7 = Chembox Hazards
EUClass =
NFPA-H = 2
NFPA-F = 0
NFPA-R = 2
NFPA-O = ox
RPhrases =
SPhrases =

Sodium metabisulfite or sodium pyrosulfite (IUPAC spelling; Br. E. sodium metabisulphite or sodium pyrosulphite) is an inorganic compound of chemical formula Na2S2O5. The name is sometimes referred to as "disodium" (metabisulfite, etc). It is used as a disinfectant, antioxidant and preservative agent.


Food additive

It is used as a food additive, mainly as a preservative and is sometimes identified as E223.

It may cause allergic reactions in those who are sensitive to sulfites.

It is present in many dilutable squashes (i.e. fruit juice concentrates) and in candy bars such as Mounds. [ [ ] ]

Sodium metabisulfite and potassium metabisulfite are the primary ingredients in Campden tablets, used for wine and beer making.

The acceptable daily intake is up to 0.7 mg per kg of body weight. Sodium metabisulfite has no side effects; it is oxidised in the liver to harmless sulphate and excreted in the urine. [ [ : E-numbers : E223: Sodium disulphite ] ]

anitization / Cleaning agent

It is commonly used in homebrewing preparations to sanitize equipment. It is used as a cleaning agent for potable water reverse osmosis membranes in desalination systems. It is also used to remove chloramine from drinking water after treatment.

Other uses

Concentrated potassium metabisulfite can be used to remove tree stumps. The "Stump-Out" brand has 98% potassium metabisulfite, and causes degradation of lignin in the stumps, facilitating removal. []

It is also used as an excipient in some tablets, such as paracetamol.

Chemical properties

When mixed with water, sodium metabisulfite releases sulfur dioxide (SO2), a pungent, unpleasant smelling gas that can also cause breathing difficulties in some people. For this reason, sodium metabisulfite has fallen from common use in recent times, with agents such as hydrogen peroxide becoming more popular for effective and odorless sterilization of equipment. Released sulfur dioxide however makes the water a strong reducing agent.


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Look at other dictionaries:

  • sodium metabisulfite — sodium meta·bi·sul·fite .met ə .bī səl .fīt n a compound Na2S2O5 used as an antioxidant in pharmaceutical preparations * * * [NF] an antioxidant, Na2S2O5, used in pharmaceutical preparations …   Medical dictionary

  • sodium metabisulfite — noun : a compound Na2S2O5 produced as an anhydrous solid or in aqueous solutions and used chiefly as a reducing agent, bleaching agent, and antichlor, in preserving foods and silage, as an antiseptic especially in the fermentation industries, and …   Useful english dictionary

  • Sodium bisulfite — Sodium bisulfite …   Wikipedia

  • Sodium sulfite — anhydrous …   Wikipedia

  • Sodium dithionite — Sodium dithionite …   Wikipedia

  • sodium bisulfite — noun also sodium acid sulfite : either of two salts usually obtained by passing sulfur dioxide through a solution of sodium carbonate: a. : an unstable crystalline salt NaHSO3 that is known especially in solution and forms sodium metabisulfite on …   Useful english dictionary

  • Sodium dithionate — Chembox new Name = Sodium dithionate ImageFile = Sodium dithionate 2D.png ImageName = Sodium dithionate IUPACName = Sodium dithionate OtherNames = Sodium metabisulfate Section1 = Chembox Identifiers CASNo = 7631 94 9 Section2 = Chembox Properties …   Wikipedia

  • sodium metabisulphite — /soʊdiəm mɛtəbaɪˈsʌlfaɪt/ (say sohdeeuhm metuhbuy sulfuyt) noun a white crystalline solid, Na2S2O5, which is the chief constituent of commercial dry sodium bisulphite, used as a food preservative. Also, sodium metabisulfite, sodium pyrosulphite …   Australian English dictionary

  • sodium sulfite — noun : a sulfite of sodium: as a. : the crystalline normal salt Na2SO3 used chiefly as a reducing agent, bleaching agent, and antichlor, in photographic developing and fixing baths, and in preserving foods b. : sodium bisulfite a c …   Useful english dictionary

  • metabisulfite — meta·bi·sul·fite or chiefly Brit meta·bi·sul·phite .bī səl .fīt n a salt containing the bivalent anion S2O52 obtained by heating a bisulfite see SODIUM METABISULFITE …   Medical dictionary

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