Aluminium phosphate Formula

Aluminium (III) phosphate, is an inorganic salt found in some minerals and used by the chemical as catalyst and by the pharmaceutical industry to obtain chemotherapeutics drugs.

Formula and structure: The aluminium phosphate chemical formula is AlPO₄ and its molar mass is 121.9529 g mol^-1. Aluminium phosphate mostly exists in nature as the anhydrous salt AlPO₄. The dihydrate and pentahydrate forms also exist in nature: AlPO₄.2H₂O and AlPO₄.5H₂O. The molecule is formed by the phosphate an anion PO₄^3- and the aluminium cation Al³⁺. The anhydrous salt structure is very similar to other minerals as quartz, with an trigonal crystal system, however the dihydrate form is similar to NaCl structure and 6 cations coordinated to 6 anions and viceversa. Its chemical structure can be written as below, in the common representations used for organic molecules.

Occurrence: Aluminium phosphate is found in nature, similarly to other aluminium salt, is a mineral: the berlinite. The dihydrate form is found in the minerals: variscite and meta-variscite. The major reserves of these minerals are in Australia and Southern Africa.

Preparation: Aluminium phosphate is extracted from the minerals berlinite, variscite and meta-variscite. Chemical methods to prepare it are not very extended or related in literature.

Physical properties: Aluminium phosphate is an odorless, white crystalline powder. Its density is 2.567 g mL^-1. The melting point is 1800 ºC and above this temperature, aluminium phosphate decomposes. It is insoluble in water but slightly soluble in hydrochloric acid and nitric acid.

Chemical properties: Aluminium phosphate does not have only the structure of quartz SiO₄, it has also the chemical properties of it. Aluminium phosphate presents piezoelectric properties. Moreover, aluminium phosphate exhibits chirality, an characteristic very common in organic compound but so rare in inorganic salts.

Uses: Aluminium phosphate is uses in electrical and electronic industries due its properties as piezoelectric material. It is also used in the production of rubbers and adhesive. Aluminium phosphate is a component of the most used antiacids.

Health effects / safety hazards: Aluminium phosphate is very harmful to health. In high concentrations, it is irritant to skin, eyes and mucosa. It can also cause damage to the respiratory system. It is not flammable and it does not react with other chemical compounds.