This film is about indicators for acids and bases. To find out whether a liquid is acidic or alkali, indicators are used to measure pH levels. The pH level is a measure for the properties acidic, neutral and alkaline in aqueous solutions. It ranges from 0 for extremely acidic to 14 for extremely alkaline. Pure water is neutral and is in the middle of the scale with a pH value of 7. With the help of various experiments, this film shows how to measure the pH levels of aqueous solutions.