A Discussion on the Nonexistence of Negative pH and pH > 14

Abstract

The main objective of this article is focused on a discussion on the range of pH which is defined to be 0 ≤ pH ≤ 14. However, ambiguities surrounding the range of pH still persist in the literature, so to say, the existence of pH beyond the aforesaid range (that is, negative pH values and pH values exceeding 14) has often been reported. Herein, we like to underscore the facts that the possibility of having a solution of pH < 0 or pH > 14 essentially accompanies the violation of fundamental thermodynamic consequences, which in turn warrants the care that must be exercised regarding the conclusion of range of pH in a solution under study, as well as the nature of the solution which the concept of pH is being applied to. In a genuine sense of the term, the pH scale should be applied to report the acidity or basicity of a dilute aqueous solution along with an appropriate mention of the experimental temperature. For very highly acidic or basic solutions one should resort to an appropriate scale of acidity or basicity.