What is the function of an indicator in chemistry?

An indicator in chemistry serves a vital function by changing color in response to specific pH levels or the presence of certain ions. This property allows indicators to visually signal whether a solution is acidic, neutral, or basic. For instance, phenolphthalein is an indicator that turns from colorless in acidic conditions to pink in basic conditions, providing an observable cue for those conducting titrations or other experiments involving acid-base chemistry.

In practice, indicators are invaluable in titration processes where they indicate the endpoint of a reaction between an acid and a base. They help chemists determine the exact point at which a reaction has proceeded to the desired extent without needing complex equipment, making them essential tools in both educational and research settings. This color change occurs due to structural changes in the indicator molecules as they interact with the changing environmental conditions in the solution, helping to provide clarity in various analytical processes.