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.
Symbol for the negative decadic logarithm of the H + ion concentration (measured in moles per liter); a solution with pH 7.00 (1 Ã 10 -7 g molecular weight of H +K per liter) is neutral at 22Â°C (that is, [H + ] = [OH - ]), one with a pH value of more than 7.00 is alkaline, one with a pH lower than 7.00 is acid.