Fluoroantimonic acid HFSbF₅ is a mixture of hydrofluoric acid and antimony pentafluoride, and is the strongest known superacid system. In this system, hydrofluoric acid releases the proton (H⁺), and the conjugate base (F⁻) is effectively sequestered by forming a strong coordinate bond with the fluorophilic antimony pentafluoride. The result of this coordinated bond is a large octahedral anion (SbF_{6⁻), which is a very weak nucleophile and a very weak base. The proton effectively becomes a "free proton", which accounts for the system's extreme acidity. Fluoroantimonic acid is 2(twenty quintillion) times stronger than 100% sulfuric acid. The autodissociation of fluoroantimonic acid in water and dissociation back to its constituents can be abbreviated as}

Comparison with other acids

• Fluoroantimonic acid (1990) (Ho Value = - 31.3)
• Magic acid (1974) (Ho Value = - 19.2)
• Carborane superacid (1969) (Ho Value = - 18.0)
• Fluorosulfuric acid (1944) (Ho Value = - 15.1)
• Triflic acid (1940) (Ho Value = - 14.9)

External links

Inorganic compounds | Superacids

Kwas fluoroantymonowy