- The pH value of an aqueous solution is a number describing its acidity of alkalinity. A number used to represent the acidity or alkalinity of an aqueous solution. pH 7 is neutral. Acids have a pH below 7, the lower the pH, the more acidic the solution. Bases have a pH above 7. The higher the pH, the more basic or alkaline the solution.
Forensic science glossary. John C. Brenner . 2012.