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

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

1. MgO + H3PO4 → MgHPO4 + H2O

If monomagnesium phosphate is dissolved in water, it forms phosphoric acid and deposits a solid precipitate of dimagnesium phosphate trihydrate:

1. 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.

See also

• Magnesium phosphate

References