Hexafluorophosphoric_acid
Hexafluorophosphoric acid
Chemical compound
Hexafluorophosphoric acid refers to a family of salts produced by combining phosphorus pentafluoride and hydrofluoric acid. The idealized chemical formula for hexafluorophosphoric acid
is HPF6, which also is written H[PF]6.[3] Hexafluorophosphoric acid is only stable in solution, decomposing to HF and PF5 when dry.[4] It exothermically reacts with water to produce oxonium hexafluorophosphate (H3OPF6) and hydrofluoric acid. Additionally, such solutions often contain products derived from hydrolysis of the P-F bonds, including HPO
2F
2, H
2PO
2F, and H
3PO
4, and their conjugate bases.[5] Hexafluorophosphoric acid attacks glass. Upon heating, it decomposes to generate HF. Crystalline HPF
6 has been obtained as the hexahydrate, wherein PF−
6 is enclosed in truncated octahedral cages defined by the water and protons. NMR spectroscopy indicates that solutions derived from this hexahydrate contain significant amounts of HF.[5]
Whereas a species with the formula HPF6 remains unknown, the analogous molecular hexafluoroarsenic acid (HAsF6) has been crystallized.[6]