What is the formula for calculating pH?

The formula for calculating pH is given by the expression pH = -log[H+]. This formula defines pH as the negative logarithm (base 10) of the concentration of hydrogen ions (H+) in a solution. The pH scale ranges typically from 0 to 14, with lower values indicating acidic conditions, higher values indicating basic conditions, and a value of 7 being neutral.

This logarithmic relationship is crucial because it reflects the way in which hydrogen ion concentration affects acidity; a tenfold increase in H+ concentration results in a one-unit decrease in pH. Therefore, understanding this formula aids in determining the acidity or basicity of a solution accurately based on its hydrogen ion concentration.

On the other hand, the other options present misconceptions or incorrect formulas regarding pH. While they may touch on related topics, they do not accurately represent the fundamental definition and calculation of pH as provided by the first formula.