A buffer contains 0.30 mol of HF and 0.15 mol of NaF in 1.0 L of solution
CHEMISTRY · Single correct · A Level · Chemistry · Acids and bases · Acids and bases
Problem
A buffer contains 0.30 mol of HF and 0.15 mol of NaF in 1.0 L of solution. A student adds 0.010 mol of NaOH(s) that dissolves completely. Which of the following best predicts the immediate direction of the pH drift?
(a) The pH will decrease slightly because the added OH− converts some F− to HF.
(b) The pH will remain essentially constant because the buffer prevents any pH change when small amounts of strong base are added.
(c) The pH will increase sharply because the buffer’s capacity toward added base has already been exceeded by the initial imbalance in HF and F−.
(d) The pH will increase slightly because the added OH− converts some HF to F−, raising the [F−]/[HF] ratio.