Problem: What is the pH of a buffer that is 0.6 M HF and 0.2 M NaF? The Ka of HF is 6.8 × 10−4.a. 3.65b. 2.69c. 3.17d. 3.50

We have to calculate the pH of a buffer that is 0.6 M HF and 0.2 M NaF.

HF is a weak acid which dissociates partially in an aqueous solution to produce H₃O⁺ and F^- ions.

HF_(aq) + H₂O_(l)⇌ F⁻_(aq) + H₃O⁺_(aq)

The fluoride ion (F^-) produced as a result of HF dissociation is the conjugate base of HF.

We will use the Henderson-Hasselbalch equation to solve this problem.

$\boxed{\mathbf{pH}\mathbf{ }\mathbf{=}\mathbf{ }{\mathbf{pK}}_{\mathbf{a}}\mathbf{ }\mathbf{+}\mathbf{ }\mathbf{log}\frac{\left[\mathbf{conjugate}\mathbf{ }\mathbf{base}\right]}{\left[\mathbf{weak}\mathbf{ }\mathbf{acid}\right]}}$