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.
What pH Tells You. A solution's pH will be a number between 0 and 14. A solution with a pH of 7 is classified as neutral. If the pH is lower than 7, the solution is acidic. When pH is higher than 7, the solution is basic. These numbers describe the concentration of hydrogen ions in the solution and increase on a negative logarithmic scale.