Sodium metabisulfite
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| Sodium Metabisulfite | ||
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| General | ||
| Other names | Sodium Pyrosulfite Sodium Disulfite |
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| Molecular formula | Na2S2O5 | |
| Molar mass | 190.1 g/mol | |
| Appearance | white powder | |
| CAS number | 7681-57-4 | |
| Properties | ||
| Density and phase | 1100 to 1200 kg/m³, solid | |
| Solubility in water | 65 g/100 ml (25 °C) | |
| Melting point | >170 °C | |
| Boiling point | ||
| Hazards | ||
| MSDS | External MSDS | |
| EU classification | ||
| NFPA 704 |
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| R-phrases | ||
| S-phrases | ||
| 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 (American spelling; English spelling is 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 sterilizer and antioxidant/preservative.
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[edit] Uses
[edit] Food additive
It is used as a food additive, mainly as a preservative and is sometimes identified as E223. As an additive, it may cause allergic reactions, particularly skin irritation, gastric irritation and asthma. It is not recommended for consumption by children.
[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] Packaging
It can be purchased in powdered form, and is also the primary ingredient in campden tablets. In solid form it ranges in color from white to slightly yellow.
[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 sterlization of equipment.
[edit] External links
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