Chemistry

Problem

The reaction

\mathrm{HF(aq) \;\rightleftharpoons\; H^+(aq) + F^-(aq)}

has

K_a = 6.6\times10^{-4}

at 25 °C. A solution is prepared with an initial concentration of

[\mathrm{HF}]_0 = 0.15\,\text{M}

and no ions present. Calculate the equilibrium concentration of

\mathrm{F^-}

(aq) at 25 °C. Report your answer to three significant figures.