Chemists describe the acidity by means of the pH scale. Pure water is neither acidic nor basic; it is neutral with a pH of 7. Acids have a pH less than 7. The lower the pH is, the more acidic a substance will be. The pH scale is logarithmic. That means that if we compare two liquids, one with a pH of 6 and the other with a pH of 3, we cannot say that the former is twice as acidic as the latter. In fact, it is 1000 times more acidic. Each change of 1 pH unit represents a change in acidity of.
