Chemistry

Problem

Hydrofluoric acid dissociates according to HF(aq) ⇌ H

^{+}

(aq) + F

^{-}

(aq) with

K_a = 6.8 \times 10^{-4}

at 25 °C. Determine the equilibrium concentration of F

^{-}

(aq) (in mol L

^{-1}

) in a 0.20 M solution of HF(aq) prepared at this temperature.