What is Magnesium phosphate

Magnesium phosphate is a general term for magnesium salts and phosphates that occur in several forms and in several hydrated forms.

Monomagnesium phosphate:

Monomagnesium phosphate is a form of magnesium phosphate.It is a magnesium salt of phosphoric acid with the chemical formula Mg(H2PO4)2.Dihydrates and tetrahydrates are also known.It dissolves in water, forms phosphoric acid and precipitates a solid precipitate of Mg(HPO4).3H2O, dimagnesium phosphate.As a food additive, used as an acidity regulator, the E number is E343.

Dimagnesium phosphate:

Dimagnesium phosphate is a chemical compound with the molecular formula MgHPO4.It is the Mg2+ salt of monohydrogen phosphate. Trihydrates are well known and occur in mineral form.It can be formed by the reaction of stoichiometric magnesium oxide with phosphoric acid.

MgO + H₃PO₄ → MgHPO₄ + H₂O

Dissolve monomagnesium phosphate in water to generate phosphoric acid, and precipitate solid precipitation of dimagnesium hydrogen 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.

Trimagnesium Phosphate: 

Trimagnesium phosphate describes an inorganic compound with the molecular formula Mg3(PO4)2.xH2O.They are magnesium salts of phosphoric acid with different amounts of water of crystallization: x = 0, 5, 8, 22.The octahydrate is formed when stoichiometric amounts of monomagnesium phosphate (tetrahydrate) react with magnesium hydroxide.

Mg(H2PO4)2•4H2O + 2 Mg(OH)2 → Mg3(PO4)2•8H2O

Octahydrate occurs in nature in the form of the mineral boronite.The anhydrous compound can be obtained by heating the hydrate to 400 °C.It is isostructural with cobalt(II) phosphate.Metal ions occupy octahedral (hexacoordinated) and pentacoordinated ratios of 1:2.