A 0.020 M aqueous solution of potassium fluoride (KF) at 25 °C has a measured pH of 8.20. Assume ideal behavior and Kw=1.0×10−14.
a. Calculate [OH−] in the solution and determine Kb for F−. Show all steps.
b. From your result in part (a), calculate pKa for HF.
c. HF is a much weaker acid than HCl (pKa≈−7). Using your calculated pKa value and structural arguments, explain this difference in acidity.
d. Predict qualitatively whether HI would be a stronger or weaker acid than HF and provide two structural or energetic reasons for your prediction.