Module 31 of 39 · Media
pH and pOH
The pH scale
The pH scale is a logarithmic scale that describes the concentration of H⁺ ions in a solution. pH is related to [H⁺] by the formula:
pH = -log[H⁺]
In any solution, the product of the hydrogen ion, H⁺, concentration and hydroxide ion, OH⁻, concentration is a constant.
-Water dissociates into H⁺ and OH⁻ ions.
The pH scale is a logarithmic scale that describes the concentration of hydrogen ions, H⁺ , in solution: pH = -log[H⁺]. The H⁺ concentration is related to the OH⁻ concentration:
[H⁺][OH⁻] =10⁻¹⁴. As [H⁺] increases, [OH⁻] decreases, and vice-versa. The pH of water is 7. In water the H⁺ concentration is equal to the OH⁻ concentration. Thus, water is neutral.