In a titration, what is the primary purpose of adding an indicator?

• A. To act as the titrant by reacting stoichiometrically with the analyte
• B. To increase the analyte concentration so that less titrant is required
• C. To produce a visible signal (usually a color change) that marks when the titration has reached the end point, close to the equivalence point
• D. To buffer the solution so the pH remains constant throughout the titration

Answer: (C)

Verified step by step guidance

1. Understand that in a titration, the goal is to determine the point at which the amount of titrant added exactly reacts with the analyte, known as the equivalence point.
2. Recognize that the equivalence point itself may not always be directly observable because it does not necessarily produce a visible change in the solution.
3. Learn that an indicator is a chemical substance added in small amounts that undergoes a distinct and visible change, often a color change, at or near the equivalence point.
4. Know that the indicator does not participate as a titrant or alter the concentration of the analyte; its role is solely to signal the end point of the titration.
5. Conclude that the primary purpose of adding an indicator is to provide a visible signal (such as a color change) that marks when the titration has reached the end point, which is close to the equivalence point.