A pH scale chart includes a list of all the possible values along the pH scale and whether each value is acidic, neutral or basic. Each pH value has a color assignment that corresponds to its color in a pH indicator test. Additionally, pH scale charts often include other information such as examples of solutions that fall near a given pH value or the concentration of hydrogen ions present within each pH value relative to distilled water.
PH is a chemical property that describes the amount of hydrogen ions within a solution. A substance with a high concentration of hydrogen ions has a low pH and is an acid. A substance with a low concentration of hydrogen ions has a high pH, and is a base. Pure water has a pH of 7, which is in the middle of the pH scale. Water is neither as an acid or a base, but a neutral solution.
Examples of acids include the digestive fluids in the stomach, vinegar and soda. Examples of bases include baking soda, bleach and liquid drain cleaner. Substances that do not easily undergo pH changes are buffers and may be present in solutions in order to stabilize them.