| Sodium metabisulfite | |
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| Other names | Sodium pyrosulfite Sodium disulfite |
| Identifiers | |
| CAS number | 7681-57-4  |
| 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 |
 0
2
0
|
| Related compounds | |
| Other anions | Sodium sulfite Sodium bisulfite |
| Other cations | Potassium metabisulfite |
| Related compounds | Sodium dithionite Sodium thiosulfate Sodium sulfate |
| (what is this?) (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| 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 |
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]
It is present in many dilutable squashes (i.e. fruit juice concentrates) and in candy bars such as Mounds.[2]
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.[3]
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.[4]
It is also used as an excipient in some tablets, such as paracetamol.
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
- ^ http://www.ific.org/publications/brochures/asthmabroch.cfm
- ^ FoodFacts.com
- ^ Food-Info.net : E-numbers : E223: Sodium disulphite
- ^ http://www.bonideproducts.com/lbonide/msds/msds271.pdf
External links
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