In a titration, what is typically used to determine the endpoint?

In a titration, the endpoint is typically determined by a change in color, which indicates that the reactants have reacted in stoichiometric proportions. This change is often achieved using an indicator, a substance that changes color at a specific pH or concentration level. For example, phenolphthalein turns from colorless to pink at a pH around 8.2, signaling that the solution has reached its endpoint for a typical acid-base titration.

The use of color change allows the experimenter to visually identify when the titration is complete without the need for complex instrumentation. This method is particularly effective because it provides a clear and immediate indication that the titration has reached the desired level of reaction, allowing for more accurate results.

Other methods, such as measuring the temperature, pressure, or total volume of the solution, do not provide the same direct indication of completion for a titration. Temperature changes may occur but are not definitive for endpoint detection, pressure is relevant in gas-producing reactions but not typically in titrations, and the total volume measurement doesn’t accurately represent the reaction's completion. Therefore, the change in color serves as a reliable and straightforward indicator for determining the endpoint in a titration.