calculate the pH of a solution after .054 moles of KOH is added to a 1.0L buffer solution of .25M HF (Ka=7.1 x 10^-4) and .10M KF
millimols KF = 1000 mL x 0.1M = 100
millimols HF - 1000 nK x 0.25 = 250
mmols KOH added = 54
.......HF + OH^- ==> F^- | H2O
I......250...0......100
added.......54...............
C......-54.-54.......+54
E......196...0........54........
Then pH = pKa + log (base)/(acid)
Substitute the E line into the HH equation and solve for pH.