How is pH expressed in relation to hydrogen ion concentration?

pH is defined as the negative logarithm of the hydrogen ion concentration in a solution. This means that when you take the concentration of hydrogen ions (expressed in moles per liter), you calculate the logarithm of that concentration and then take the negative of that value. This relationship allows for a more manageable scale when dealing with the wide range of hydrogen ion concentrations found in various solutions.

The logarithmic scale is particularly useful because it compresses the large variations in ion concentration into a smaller numeric range that is easier to understand and work with. For instance, a change of 1 pH unit corresponds to a tenfold change in hydrogen ion concentration, which highlights significant variations in acidity or alkalinity.

This foundational concept is critical in fields such as wastewater treatment, where maintaining appropriate pH levels is essential for chemical reactions, biological processes, and overall system performance. Understanding how pH relates to hydrogen ion concentration helps professionals monitor and control wastewater treatment processes effectively.