Summary:
- An acid-base indicator displays different colors when in the presence of an acid or a base.
- An indicator is a weak acid that ionizes within a known pH range, usually about 2 pH units.
- To be useful as an indicator, the two forms must be different colors.
- Universal indicator displays the entire rainbow of colors from low pH to high pH (see Figure below).
- Universal indicator is used to make pH paper, which can be used to quickly test solutions for their approximate pH.
- Use the resource below to answer the questions that follow.