Calcium phosphate

Description

Calcium Phosphate is the calcium salt of phosphoric acid with widely used applications. It occur abundantly in nature in several forms and are the principal minerals for the production of phosphate fertilizers and for a range of phosphorus compounds. For example, the tribasic variety (precipitated calcium phosphate), Ca3(PO4)2, is the principal inorganic constituent of bone ash. The acid salt Ca(H2PO4)2, produced by treating mineral phosphates with sulfuric acid, is employed as a plant food and stabilizer for plastics. It is a natural constituent of mammals, and it is a component of bone replacement transplants in much higher amounts with no toxicological problems.

Chemical properties

Tricalcium phosphate is white solid, insoluble in water; reactive with silicon oxide and carbon at electric furnace temperature yielding phosphorus vapor; reactive with H2SO4 to form, according to the proportions used, phosphoric acid, or dicalcium hydrogen phosphate, CaHPO4, white solid, insoluble; or calcium dihydrogen phosphate, Ca(H2PO4)2·H2O, white solid, soluble. pKsp = 28.70.

The Uses of Calcium phosphate

Tribasic calcium phosphate occurs in nature as minerals, oxydapatite, whitlockite, voelicherite, apatite, phosphorite. It is an anticaking agent and calcium source that is a white powder that is almost insoluble in water. Some are similar to the monobasic and dibasic salts. It is used in fertilizers, dental products, ceramics and polishing powder. Some other important applications are in plastics as a stabilizer; as an anticaking agent; as a nutrient supplement in cattle food; for clarifying sugar syrup; as a mordant in dyeing textiles; and as a buffer to control pH.

Preparation

Tribasic calcium phosphate is obtained from naturally occurring minerals for fertilizer applications. The compound may be prepared in the laboratory by the reaction of sodium phosphate with calcium chloride with excess of ammonia. Also, it can be prepared by treatment of calcium hydroxide with phosphoric acid:
2H3PO4 + 3Ca(OH)2 → Ca3(PO4)2 + 6H2O

Definition

ChEBI: Tricalcium bis(phosphate) is a calcium phosphate.

Industrial uses

Calcium phosphate [Ca₃(PO₄)₂] finds applications as a supplement for animal feed, as a fertiliser, in the manufacture of glass and in dental products.