Trimagnesium phosphate describes
inorganic compound
In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...
s with formula Mg
3(PO
4)
2.xH
2O. They are
magnesium
Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...
acid salts of
phosphoric acid, with varying amounts of
water of crystallization
In chemistry, water(s) of crystallization or water(s) of hydration are water molecules that are present inside crystals. Water is often incorporated in the formation of crystals from aqueous solutions. In some contexts, water of crystallization is ...
: x = 0, 5, 8, 22.
The octahydrate forms upon reaction of stoichiometric quantities of
monomagnesium phosphate
Monomagnesium phosphate is one of the forms of magnesium phosphate. It is a magnesium acid salt of phosphoric acid
Phosphoric acid (orthophosphoric acid, monophosphoric acid or phosphoric(V) acid) is a colorless, odorless phosphorus-contain ...
(tetrahydrate) with
magnesium hydroxide
Magnesium hydroxide is the inorganic compound with the chemical formula Mg(OH)2. It occurs in nature as the mineral brucite. It is a white solid with low solubility in water (). Magnesium hydroxide is a common component of antacids, such as milk ...
.
:Mg(H
2PO
4)
2•4H
2O + 2 Mg(OH)
2 → Mg
3(PO
4)
2•8H
2O
The octahydrate is found in nature as the mineral
bobierrite.
The anhydrous compound is obtained by heating the hydrates to 400 °C. It is isostructural with cobalt(II) phosphate. The metal ions occupy both
octahedral (six-coordinate) and pentacoordinate sites in a 1:2 ratio.
Safety
Magnesium phosphate tribasic is listed on the FDA's
generally recognized as safe, or GRAS, list of substances.
See also
*
Magnesium phosphate
Magnesium phosphate is a general term for salts of magnesium and phosphate
In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthop ...
References
{{Phosphates
Acid salts
Phosphates
Magnesium compounds
E-number additives