Sodium Metabisulfite

Sodium metabisulfite
Identifiers
CAS number 7681-57-4 Yes check.svgY
PubChem 24346
EC number 231-673-0
RTECS number UX8225000
Properties
Molecular formula Na2S2O5, Na-O-(S=O)-O-(S=O)-O-Na
Molar mass 190.107 g/mol
Appearance white powder
Density 1.48 g/cm3
Melting point

>170 °C (begins at 150 °C)

Solubility in water 54 g/100 ml
Hazards
MSDS Mallinckrodt MSDS
EU Index 016-063-00-2
EU classification Harmful (Xn)
Irritant (Xi)
R-phrases R22, R31, R41
S-phrases (S2), S26, S39, S46
NFPA 704
NFPA 704.svg
0
2
0
Related compounds
Other anions Sodium sulfite
Sodium bisulfite
Other cations Potassium metabisulfite
Related compounds Sodium dithionite
Sodium thiosulfate
Sodium sulfate
 Yes check.svgY (what is this?)  (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

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.

Contents

  • 1 Uses
    • 1.1 Food additive
    • 1.2 Sanitization / Cleaning agent
    • 1.3 Other uses
  • 2 Chemical properties
  • 3 References
  • 4 External links

Uses

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, including respiratory reactions in asthmatics as well as in those who do not identify with the condition.1

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 sulfate and excreted in the urine.2

Sanitization / Cleaning agent

It is commonly used in homebrewing and winemaking 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 sodium metabisulfite can be used to remove tree stumps. Some brands contain 98% sodium metabisulfite, and cause degradation of lignin in the stumps, facilitating removal.3

It is also used as an excipient in some tablets, such as paracetamol. Approximately 0.5 mg is used in epinephrine, also known as the EpiPen Auto-Injector.

A very important health related aspect of this substance is that it can be added to a blood smear in a test for sickle cell anaemia (and other similar forms of haemoglobin mutation). The substances causes defunct cells to sickle (through a complex polymerisation) hence confirming disease.

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.

References

  1. ^ http://www.ific.org/publications/brochures/asthmabroch.cfm
  2. ^ Food-Info.net : E-numbers : E223: Sodium disulphite
  3. ^ http://www.bonideproducts.com/lbonide/msds/msds271.pdf

External links

  • International Chemical Safety Card 1461

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This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article http://en.wikipedia.org/wiki/Sodium_Metabisulfite. Additionally, in some cases elements from this article might be licensed under a different license. Please refer to the original article to check the license status http://en.wikipedia.org/wiki/Sodium_Metabisulfite.