Sodium trimetaphosphate

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Sodium trimetaphosphate[1]
Sodium trimetaphosphate.png
Other names
Sodium trimetaphosphate
7785-84-4 YesY
EC Number 232-088-3
Jmol 3D model Interactive image
PubChem 24579
Molar mass 305.885 g/mol
Appearance colorless or white crystals
Density 2.49 g/cm3 (anhydrous)
1.786 g/cm3 (hexahydrate)
Melting point 53 °C (127 °F; 326 K) (hexahydrate, decomposes to anyhdrous)
22 g/100 mL
Solubility insoluble in alcohol
1.433 (hexahydrate)
triclinic (hexahydrate)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Sodium trimetaphosphate (also STMP), with formula Na3P3O9, is a metaphosphate of sodium. It has the empirical formula NaPO3. It is the sodium salt of trimetaphosphoric acid. It is a colourless solid that finds specialised applications in food and construction industries. STMP is prepared by heating sodium polyphosphate at a few hundred degrees. [2]

Although drawn with a particular resonance structure, the trianion has D3d symmetry.


  1. ^ Lide, David R. (1998). Handbook of Chemistry and Physics (87 ed.). Boca Raton, FL: CRC Press. pp. 4–86. ISBN 0-8493-0594-2. 
  2. ^ Klaus Schrödter, Gerhard Bettermann, Thomas Staffel, Friedrich Wahl, Thomas Klein, Thomas Hofmann "Phosphoric Acid and Phosphates" in Ullmann’s Encyclopedia of Industrial Chemistry 2008, Wiley-VCH, Weinheim. doi:10.1002/14356007.a19_465.pub3