Which expression best defines pH?

The pH scale is a logarithmic scale used to specify the acidity or basicity of an aqueous solution. It is defined as the negative base-10 logarithm of the concentration of hydrogen ions, represented by [H+]. This relationship is mathematically expressed as pH = -log [H+].

When the concentration of hydrogen ions is high, the pH is low, indicating an acidic solution. Conversely, when the concentration of hydrogen ions is low, the pH is high, indicating a basic or alkaline solution. The negative logarithm emphasizes that as [H+] increases, pH decreases and vice versa.

Understanding this relationship is crucial for medical technologists, as pH plays a significant role in biochemical reactions and overall physiological functions.