The hydrogen ion concentration of a solution is indicated by its
___ value.

The hydrogen ion concentration of a solution is indicated by its pH value.

Explanation:

A measure of acidity or alkalinity of water soluble substances (pH stands for 'potential of Hydrogen'). A pH value is a number from 1 to 14, with 7 as the middle point.Under normal circumstances this means that the concentration of hydrogen ions in acidic solution can be taken to be equal to the concentration of the acid. The pH is then equal to minus the logarithm of the concentration value. Values below 7 indicate acidity which increases as the number decreases, 1 being the most acidic.The pH of a solution is a measure of hydrogen ion concentration, which in turn is a measure of its acidity. Pure water dissociates slightly into equal concentrations of hydrogen and hydroxyl (OH−) ions. For a neutral solution, [H+] is 10−7, or pH = 7.