10.2 pH and pOH

pH

The level of acidity of a solution directly relates to the concentration of ${H^+}$ (${H_3O^+}$) and {OH^–}. To measure them, the pH scale is used, a logarithmic scale that ranges from 0 to 14. While a pH below 0 or above 14 is possible, they are very unlikely. The formula for pH is {–log[H⁺]}. The fact that the scale is logarithmic means it scales by 10x, and the fact that it is negative means that a lower pH is indicative of a higher ${[H^+]}$, making it more acidic. So, something with a pH of 2 is ten times more acidic than something with a pH of 3.