What is the definition of pH in chemical terms?

The definition of pH in chemical terms specifically relates to hydrogen ion concentration in a solution. pH is a logarithmic scale used to quantify the acidity or basicity of a solution and is defined as the negative base 10 logarithm of the concentration of hydrogen ions (([H^+])) in moles per liter. This means that a lower pH value indicates a higher concentration of hydrogen ions and, consequently, a more acidic solution, while a higher pH value indicates a lower concentration of hydrogen ions and a more basic solution.

This definition is foundational in chemistry because it provides a straightforward and numerical way to describe how acidic or alkaline a solution is, which is crucial in fields ranging from biology to environmental science and industrial applications. Understanding pH is essential for predicting the behavior of various chemical reactions, the solubility of substances, and the interactions between different compounds in a solution.