Determine the pH during the titration of 14.7 mL of 0.218 M nitric acid by 0.138 M potassium hydroxide at the following points:
(1) Before the addition of any potassium hydroxide _______
(2) After the addition of 11.6 mL of potassium hydroxide _______
(3) At the equivalence point _________
(4) After adding 29.2 mL of potassium hydroxide __________