any of the major appearances or aspects in which a thing of varying modes or conditions manifests itself to the eye or mind. 2. a stage in a process of change or development: Each phase of life brings its own joys. 3. a side, aspect, or point of view: This is only one phase of the question.
The pH of a neutral solution is 7. At this pH, the solution has equal concentrations of both the H+ and OH- ions, which is 10^-7 mole/litre. The presence of both the hydrogen and hydroxyl ions in equimolar concentrations makes the solution neutral.
pH is potential hydrogen. It is on a scale from 1 to 14 where 7 is neutral. A pH of .5 or 1 is all hydrogen, so it's like the sun, so nothing is going to live in that environment. Oxidation is based on electrons.