Tricalcium phosphate

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Properties

General

Name Tricalcium phosphate
Chemical formula Ca3(PO4)2
Appearance White amorphous powder

Physical

Formula weight 310.18 g/mol
Melting point Liquifies under high pressure at 1670 K (1391 °C)
Boiling point N/A
Density 3.14 ×103 kg/m3
Solubility 0.002 g in 100g water

Thermochemistry

ΔfH0liquid -999.8 kJ/mol
ΔfH0solid -982.3 kJ/mol (alpha form)
-984.9 kJ/mol (beta form)
S0solid 57.58 J/(mol·K) (alpha form)
56.4 J/(mol·K) (beta form)

Safety

Ingestion Causes irritation to the gastrointestinal tract.
Inhalation Causes irritation to the respiratory tract.
Skin May cause skin irritation.
Eyes May cause irritation and damage to the cornea.
More info Hazardous Chemical Database

SI units were used where possible. Unless otherwise stated, standard conditions were used. Disclaimer and references

Tricalcium phosphate is a compound with formula Ca3(PO4)2. It is also known as calcium orthophosphate, tertiary calcium phosphate, tribasic calcium phosphate, or "bone ash" (calcium phosphate being one of the main combustion products of bone).

It has an alpha and a beta crystal form, the alpha state being formed at high temperatures. As rock, it is found in Whitlockite.

Related salts

Dicalcium phosphate CaHPO4 (also calcium monohydrogen phosphate)
Monocalcium phosphate Ca(H2PO4)2 (also calcium dihydrogen phosphate)
Calcium pyrophosphate Ca2P2O7 (occurs as alpha, beta and gamma phases)

General case

In minerals, "calcium phosphate" refers to minerals containing calcium ions (Ca2+) together with orthophosphates (PO43-), metaphosphates or pyrophosphates (P2O74-) and occasionally hydrogen or hydroxide ions.

Especially, the common mineral apatite has formula Ca5(PO4)3X, where X is F, Cl, OH, or a mixture; it is hydroxyapatite if the extra ion is mainly hydroxide. Much of the "tricalcium phosphate" on the market is actually powdered hydroxyapatite.

Natural occurrence

It is found in nature as a rock in Morocco, Israel, Egypt, and Kola (Russia) and in smaller quantities in some other countries. The natural form is not completely pure, and there are some other components like sand and lime which can change the composition. In terms of P2O5, most calcium phosphate rocks have a content of 30% to 40% P2O5 in weight.

The skeletons and teeth of vertebrate animals are composed of calcium phosphate, mainly hydroxylapatite.

Uses

Tricalcium phosphate is used in powdered spices as an anti-caking agent.

Calcium phosphate is an important raw material for the production of phosphoric acid and fertilizers, for example in the Odda process.

Calcium phosphate is also a raising agent (food additives) E341. Is a mineral salt found in rocks and bones, it is used in cheese products.

It is also used as a nutritional supplement. There is some debate about the different bioavailabilities of the different calcium salts.

It is commonly used in porcelain and dental powders, and medically as an antacid or calcium supplement, although calcium carbonate is more common in this regard.

Another practical application of the compound is its use in gene transfection. The calcium ions can make a cell competent (a euphemism for "rip holes in its membrane") to allow exogenous genes to enter the cell by diffusion. A heat shock afterwards then invokes the cell to repair itself. This is a quick and easy method for transfection, albeit a rather inefficient one.

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