Sodium hexametaphosphate
| Names | |
|---|---|
| Other names
Calgon S
Glassy sodium Graham's salt Hexasodium metaphosphate Metaphosphoric acid, hexasodium salt SHMP Sodium polymetaphosphate | |
| Properties | |
| (NaPO3)6 | |
| Molar mass | 611.7704 g/mol |
| Appearance | Crystalline solid |
| Density | 2.484 g/cm3 |
| Melting point | 628 °C (1,162 °F; 901 K) |
| Boiling point | 1,500 °C (2,730 °F; 1,770 K) |
| Soluble | |
| Solubility | Insoluble in organic solvents |
| Hazards | |
| Safety data sheet | Sigma-Aldrich |
| Lethal dose or concentration (LD, LC): | |
| LD50 (Median dose)
|
3,053 mg/kg (rat, oral) |
| Related compounds | |
| Related compounds
|
Phosphoric acid |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Sodium hexametaphosphate or sodium polymetaphosphate is a chemical compound, a hexamer with the formula (NaPO3)6.
Contents
Properties
Chemical
Sodium hexametaphosphate hydrolyzes in aqueous solution, particularly under acidic conditions, to sodium trimetaphosphate and sodium orthophosphate.
Thermoreduction of this compound using carbon or Al powder with sand (silicon dioxide) yields white phosphorus. While other phosphorus-containing compounds may be used, sodium hexametaphosphate has one of the highest concentration of elemental P per molecule (30.37%), among the more readily available phosphorus compounds, thus it is the better starting material. While phosphoric acid has a slightly higher concentration of P (31.60 %), it is difficult to properly reduce it, due to its unwillingness to give up water even at high temperatures, which may interfere with the reduction reaction.
Physical
Sodium hexametaphosphate is a hard crystalline solid, insoluble in most solvents.
Availability
Sodium hexametaphosphate is sold in many hardware stores as water deflocculant.
Preparation
Sodium hexametaphosphate can be made by dehydrating monosodium phosphate to sodium acid pyrophosphate and then to sodium hexametaphosphate.
Projects
- Water filtration
- Make elemental phosphorus
Handling
Safety
Sodium hexametaphosphate has low toxicity and doesn't require special handling.
Storage
In closed bottles.
Disposal
No special disposal is required. Discard it as you wish.
