Sodium hexametaphosphate
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| General | |
|---|---|
| CAS number | 10124-56-8 |
| Chemical formula | (NaPO3)6 |
| Appearance | White, odorless, crystalline powder |
| Physical | |
| Formula weight | 611.77 |
| Melting point | 640.0 °C |
| Boiling point | ? |
| Density | 1.2 g/cm3 |
| Crystal structure | ? |
| Solubility | Easily soluble in water |
| Safety | |
| NFPA 704 |
0
1
0
|
| Ingestion | May cause irritation |
| Inhalation | Irritant |
| Skin | May cause irritation |
| Eyes | Irritant |
| LD50 | 6200 mg/kg |
|
SI units were used where possible. Unless otherwise stated, standard conditions were used. |
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Sodium hexametaphosphate (SHMP) (E452(i)) is correctly speaking a hexamer of composition (NaPO3)6. "Sodium hexametaphosphate" of commerce is a mixture of polymeric metaphosphates, of which the hexamer is one, and is usually the compound referred to by this name. It is more correctly termed sodium polymetaphosphate, CAS 50813-16-6. It is prepared by melting monosodium orthophosphate, followed by rapid cooling. SHMP hydrolyzes in aqueous solution, particularly under acidic conditions, to sodium trimetaphosphate and sodium orthophosphate. SHMP is used as a sequestrant and has applications in a wide variety of industries, including as a food additive. Sodium carbonate is sometimes added to SHMP to raise the pH to 8.0-8.6, which produces a number of SHMP products used for water softening and detergents.
[edit] Other names
- Calgon S
- glassy sodium
- Graham's Salt
- hexasodium metaphosphate
- hexasodium salt
- metaphosphoric acid
[edit] References
- Merck Index, 'Sodium polymetaphosphate'
- Van Wazer, John R. Phosphorus and its compounds. New York : Interscience Publishers (1958)
[edit] External links
- Links to external chemical sources
- Occupational Health and Safety Agency for Healthcare in British Columbia
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