What is "metaphosphate"

Metaphosphate \Met`a*phos"phate\, n. (Chem.) A salt of metaphosphoric acid.

n. (context chemistry English) Any salt or ester of metaphosphoric acid.

A metaphosphate ion is an oxyanion that has the empirical formula . The structure of a metaphosphate ion can be described as being made up of PO structural units in which each unit shares two corners with another unit. This can come about in two ways.

• Formation of a ring, as in trimetaphosphate, illustrated.
• Formation of an infinite chain, with the same structure as in ammonium metavanadate

Metaphosphates can be considered as salts of the corresponding metaphosphoric acids (HPO) although none of these acids has been isolated. The metaphosphoric acids can be formulated as HO·PO. In comparison, phosphoric acid, HPO can be formulated as 3HO·PO and pyrophosphoric acid, HPO, as 2HO·PO.