 We're going to look at the pH of a number of buffer solutions and see how the pH changes as we add acid or base. We're going to start out, however, looking at a solution that is not a buffer, which is pure water. I've calibrated a CBL pH probe and I'm going to put it into some distilled water. Our solution starts out being relatively close to a pH of 7. We're going to add a drop of 1 molar HCl. Notice that the pH drops rapidly. Pure water is not a buffer. If we add a strong acid to it, the strong acid ionizes 100%. There's no buffering capacity in the water. The pH drops rapidly. We'll repeat this experiment with some more distilled water. Notice that the starting pH here is a little bit less than 7. This is not unusual if there's a lot of dissolved carbon dioxide in the water, which forms carbonic acid. What we're going to do is add a drop of 1 molar NaOH to the solution. Notice that the pH rises rapidly to a pH of almost greater than 12. Pure water, again, is not a very good buffer. If we add a strong base, the pH rises rapidly.