What does the pH scale measure?

The pH scale measures the concentration of hydrogen ions (H⁺) in a solution. This scale typically ranges from 0 to 14, where a lower pH value indicates a higher concentration of hydrogen ions, reflecting a more acidic solution, while a higher pH indicates a lower concentration of hydrogen ions, denoting a more alkaline (or basic) solution. The neutral point on the pH scale is around 7, which corresponds to pure water, where the concentrations of hydrogen ions and hydroxide ions (OH⁻) are equal.

Understanding the significance of the pH scale is crucial in various scientific fields, particularly chemistry, biology, and environmental science, as it impacts chemical behavior, biological processes, and ecological health. For instance, the pH of soil can affect plant growth, and the pH of water can influence aquatic life.

The other options do not relate to what the pH scale measures; temperature pertains to heat, color refers to the visual aspect of a solution, and density is a measure of mass per unit volume. These aspects are essential in their own right but are distinct from the concept measured by the pH scale.