Question

1) A buffer solution contains 0.346 M hydrofluoric acid and 0.392 M sodium fluoride .

If 0.0239 moles of potassium hydroxide are added to 125 mL of this buffer, what is the pH of the resulting solution ?
(Assume that the volume does not change upon adding potassium hydroxide. )

pH = _______

2) A student needs to prepare a buffer made from HF and KF with pH 2.904. If Ka for HF is 7.2x10^-4, what ratio of [HF]/[F-] is required?

[HF]/[F-] = ________

Answer 1

1. Since the given mixture is an example for acidic buffer, added KOH reacts with HF and forms salt hence acid concentration decreases and pH Increases.