A solution is prepared by dissolving 0.24 mol of butanoic acid and 0.25 mol of sodium butanoate in water sufficient to yield 1.00 L of solution. The addition of 0.05 mol of NaOH to this buffer solution causes the pH to increase slightly. The pH does not increase drastically because the NaOH reacts with the present in the buffer solution. The Ka of butanoic acid is 1.5 × 10-5.