Buffer Solution Calculation

Question

A buffer solution was prepared by adding 0.345 mol of sodium fluoride to 1.35L of 0.0619M hydrofluoric acid solution. Determine [H₃O⁺] at equilibrium in this buffer. Assume that the volume of the solution remains at 1.35L. K_a for HF is 6.8 x 10^-4.

Answer 1

You can use the Henderson-Hasselbach equation pH = pKa + log([F^-]/[HF])

Derived by taking -log of Ka expression

concentration of F^- is .345 moles/1.35 liters and log is base 10.

Please consider a tutor. Take care. I have assumed the NaF is completely soluble.