Answer:
The acid dissociation constant (K_a) of an acid is defined as the equilibrium constant for the dissociation of the acid in water. The equation for the dissociation of an acid HA in water can be written as follows:
HA(aq) + H2O(l) ⇌ H3O+(aq) + A-(aq)
The equilibrium constant expression for this reaction is:
K_a = [H3O+][A-] / [HA]
For the given reaction, the acid is HF, and its conjugate base is F-. Therefore, the acid dissociation constant (K_a) for HF can be expressed as:
K_a = [H3O+][F-] / [HF]