Hey, I am trying to figure out some research for a department at school, and need some chemistry info. Basically, I am comparing D2O (Heavy water) HDO (Semiheavy water) and H2O (Light water) NOW... each of them have different pH levels. What does that mean that they each have different pH levels? I know the pH is the activity of the hydrogen ion. But can someone explain that a little more clear for me? :) Does it mean they vibrate at different rates? Or what? Thanks Chem guys and galls!