Calcium phosphate - Ca3(PO4)2

What is Calcium phosphate?

Calcium phosphate is a calcium salt of phosphoric acid with a chemical formula Ca3(PO4)2. It is also known as Calcium phosphate tribasic or Tricalcium Phosphate. It appears as a white amorphous or crystalline powder which is odourless and tasteless. It is insoluble in ethanol, acetic acid but soluble in dilute nitric acid and hydrochloric acid. It slightly dissolves in water. It is found in bones, milk, teeth, and ground.

Apatite is a mineral rock which is an impure and complex form of calcium phosphate which produces tribasic calcium phosphate. An apatite is a form of phosphorite which contains calcium phosphate mixed with other compounds.

It can also be produced by reacting phosphoric acid (H3PO4) with solid calcium hydroxide Ca(OH)2

Ca(OH)2+H3PO4→Ca3(PO4)2+H2O (unbalanced)

3Ca(OH)2+2H3PO4→Ca3(PO4)2+6H2O (balanced equation)

Dibasic calcium phosphate can be produced in the former of these reactions by using an aqueous solution of calcium hydroxide. Monobasic calcium phosphate is obtained by adding excess phosphoric acid to either dibasic solution or tribasic calcium phosphate solution and letting the solution to evaporate.

Properties of Calcium phosphate – Ca3(PO4)2

Ca3(PO4)2 Calcium phosphate
Molecular Weight/ Molar Mass 136.06 to 310.20 g/mol
Density (tribasic) 3.14 g/cm³
Boiling Point Decomposes
Melting Point (tribasic) 1670°C

Uses of Calcium phosphate (Ca3(PO4)2)

  • Calcium phosphate is used as an antacid and dietary supplement in veterinary medicine.

  • It is used in medicine as calcium replenisher.

  • It is used as a buffer in food.

  • It is used stabilizer in plastics.

  • It is used in the manufacturing of milk glass.

  • It is used in the production of fertilizers.

  • It is used in the manufacture of luminescent materials.

  • It is used to clarify sugar syrups.

  • It is used in dental powders.

Calcium phosphate health risks

When the toxic doses ingested become more than 2 g/kg unusual skin sensitization occurs. Inhaling it may cause chemical pneumonitis.