Sodium hexametaphosphate

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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):
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.

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

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.

References

Relevant Sciencemadness threads