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 the measurement of acidity or alkalinity in aqueous solutions. pH is the scale of measurement of acidity or alkalinity in aqueous (water based) solutions. A neutral solution such as pure water has a pH of 7. Solutions with a lower pH are termed acidic and solutions with a higher pH are termed alkaline. pH ranges from highly acidic pH 0 to highly alkaline pH 14. The pH of the human eye is about 7.5.