Dimagnesium phosphate

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Dimagnesium phosphate
Magnesium phosphate dibasic.png
Other names
Magnesium hydrogen phosphate; Magnesium phosphate dibasic
3D model (JSmol)
ECHA InfoCard 100.028.930
E number E343(ii) (antioxidants, ...)
Molar mass 120.283 g·mol−1
Density 2.13 g/cm3 trihydrate
R-phrases (outdated) R36, R37, R38
NFPA 704
Flammability code 0: Will not burn. E.g. waterHealth code 0: Exposure under fire conditions would offer no hazard beyond that of ordinary combustible material. E.g. sodium chlorideReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
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

Dimagnesium phosphate is a compound with formula MgHPO4. It is a Mg2+ salt of monohydrogen phosphate. The trihydrate is well known, occurring as a mineral.[1]

It can be formed by reaction of stoichiometric quantities of magnesium oxide with phosphoric acid.

MgO + H3PO4 → MgHPO4 + H2O

Dissolving monomagnesium phosphate in water, forms phosphoric acid and depositing a solid precipitate of dimagnesium phosphate trihydrate:

Mg(H2PO4)2 + 3 H2O → Mg(HPO4).3H2O + H3PO4

The compound is used as a nutritional supplement, especially for infants and athletes. Its E number is E343.[2]

See also[edit]


  1. ^ Klaus Schrödter; Gerhard Bettermann; Thomas Staffel; Friedrich Wahl; Thomas Klein; Thomas Hofmann (2008). Phosphoric Acid and Phosphates. Ullmann’s Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_465.pub3.
  2. ^ relevant part of the German “Zusatzstoff-Zulassungsverordnung Archived 2012-05-18 at the Wayback Machine”, the official German implementation of the respective regulation of the European Union