Adding Strong Acids or Bases to Buffer Solutions

Now that we have this nice F/HF buffer, let's see what happens when we add strong acid or base to it. Recall that the amount of F- in the solution is 0.66M x 0.1 L = 0.066 moles and the amount of HF is 1.0 M x 0.1L = 0.10 moles. Let's double check the pH using theHenderson-Hasselbalch Approximation, but using moles instead of concentrations:

pH = pKa + log(Base/Acid) = 3.18 + log(0.066 moles F/0.10 moles HF) = 3.00