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| Names | |
|---|---|
| IUPAC name
barium(2+); dioxido(oxo)phosphanium | |
| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
| ECHA InfoCard | 100.033.951 
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| EC Number |
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PubChem CID |
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CompTox Dashboard (EPA) |
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| Properties | |
| Ba(PO3)2 | |
| Molar mass | 295.27 g/mol |
| Appearance | Powder[1] |
| Density | 3.63 g/cm3 |
| Melting point | 1,560[2] °C (2,840 °F; 1,830 K) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Barium metaphosphate is an inorganic substance with the molecular formula Ba(PO3)2. It is a colourless solid that is insoluble in water, though is soluble in acidic solutions through "slow dissolution".[3] X-ray crystallography shows that this material is composed of Ba2+ cations attached to a polyphosphate ((PO3−)n) anion.[4] A number of hydrated forms are known which are actually cyclic metaphosphates, Ba2(P4O12)·3.5H2O, Ba3(P3O9)2·6H2O.[citation needed]
Barium metaphosphate can be prepared by the reaction of barium carbonate with metaphosphoric acid:[citation needed]
or alternatively by the aqueous reaction of barium chloride and sodium metaphosphate:[citation needed] BaCl2(aq) + 2NaPO3(aq) → Ba(PO3)2 + 2NaCl
The combination of sodium and barium polyphosphate forms a low-melting glass with a high coefficient of thermal expansion. The melting point of the glass increases with barium content. This glass makes seals with low melting metals like aluminium (melting point 650 °C). Normal borosilicate glasses soften above the melting point of aluminium. This mixture is prepared by heating a mixture of diammonium phosphate, sodium carbonate, and barium carbonate.[5]
