Sodium metabisulfite
From Wikipedia, the free encyclopedia
| Sodium Metabisulfite | |
|---|---|
 |
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| Other names | Sodium Pyrosulfite Sodium Disulfite |
| Identifiers | |
| CAS number | [7681-57-4] |
| Properties | |
| Molecular formula | Na2S2O5 |
| Molar mass | 190.1 g/mol |
| Appearance | white powder |
| Density | 1100 to 1200 kg/m³ (solid) |
| Melting point |
>170 °C (begins at 150) |
| Solubility in water | 47 (20 °C) |
| Hazards | |
| NFPA 704 |
 0
2
2
OX
|
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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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 |
[edit] Uses
[edit] 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.[1]
Sodium metabisulfite and potassium metabisulfite and 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.[2]
[edit] Sterilization / 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.
[edit] Other uses
In high concentration, potassium metabisulfite can be used to remove stumps. The Stump-Out brand has 98% potassium metabisulfite, causing degradation of lignin in the stumps, thus facilitating the removal process.[3]
[edit] 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.
