Fluorophosphoric acid is the

inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...

with the formula H₂PO₃F. It is a colorless viscous liquid that solidified to a glass upon cooling.

Preparation

Fluorophosphoric acid is produced commercially by treating

phosphorus pentoxide Phosphorus pentoxide is a chemical compound with molecular formula P4 O10 (with its common name derived from its empirical formula, P2O5). This white crystalline solid is the anhydride of phosphoric acid. It is a powerful desiccant and dehydra ...

with

hydrogen fluoride Hydrogen fluoride (fluorane) is an inorganic compound with the chemical formula . This colorless gas or liquid is the principal industrial source of fluorine, often as an aqueous solution called hydrofluoric acid. It is an important feedstock i ...

. A less pure product can also be prepared by

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...

phosphorus oxyfluoride Phosphoryl fluoride (commonly called phosphorus oxyfluoride) is a compound with the chemical formula . It is a colorless gas that hydrolyzes rapidly. Synthesis and reactions Phosphorus oxyfluoride is prepared by partial hydrolysis of phosphorus p ...

, a reaction that first produces difluorophosphoric acid: :POF₃ + H₂O → HPO₂F₂ + HF The next steps give monofluorophosphoric acid: :HPO₂F₂ + H₂O → H₂PO₃F + HF

Reactions

Fluorophosphoric acid is a dibasic acid, with pK_as of 5.5 and around 8.5. The conjugate bases are the

monofluorophosphate Monofluorophosphate is an anion with the formula PO3F2−, which is a phosphate group with one oxygen atom substituted with a fluoride atom. The charge of the ion is −2. The ion resembles sulfate in size, shape and charge, and can thus form comp ...

s, which are hydrolytically robust.

References

{{inorganic-compound-stub Oxohalides Phosphorus halides Fluoro complexes