Question

The strongest known acid is fluoroantimonic acid, [H2F][SbF6]. It is 1016 times more acidic than concentrated sulfuric acid and has a pH of -31.3; it is strong enough to protonate both xenon and molecular hydrogen. It is an ionic liquid made by reacting hydrogen fluoride with antimony(V) fluoride:

2 HF + SbF5 → H2F+ + SbF6-

Explain why this acid is so strong.

Answer 1

Since ionization process depends upon breaking of the bond weaker the H-X bond, stronger the acid.

The proton from HF₂+has been popularly said to become "naked", accounting for the system's extreme acidity.In the physical sense, the acidic "proton" is never completely free (as an unbound proton) but is bound to the anion, albeit weakly. The proton hops from anion to anion in superacids.

The extreme acidity is due to the ease with which this proton is transferred to substances that cannot normally be "protonated" (such as hydrocarbons), due to the very high stability of the conjugate-base anion (such as SbF−
6) after it donates the proton.

The charge effect make it more acidic (+ charge in H2F+)