Fluoroantimonic acid

Fluoroantimonic acid 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 2×10¹⁹(twenty quintillion) times stronger than 100% sulfuric acid as a hydrogen ion donor acidic power. A 100% solution of fluoroantimonic acid has an acidic power value of −31.3 (H0 Value), and an intensely high acidity ioniser value as well.}