Difluorophosphoric acid
Difluorophosphoric acid is an inorganic compound with the formula. It is a mobile colorless strongly fuming liquid. The acid has limited applications, in part because it is thermally and hydrolytically unstable. Difluorophosphoric acid is corrosive to glass, fabric, metals and living tissue.
A method to make pure difluorphosphoric acid involves heating phosphoryl fluoride with fluorophosphoric acid and separating the product by distillation:
It is prepared by hydrolysis of phosphoryl fluoride:
Further hydrolysis gives fluorophosphoric acid:
Complete hydrolysis gives phosphoric acid:
The salts of difluorophosphoric acid are known as difluorophosphates.