Questions: In a titration, the endpoint is the point at which the indicator changes color, the pH equals the pKa, moles of acid equals moles of base.

Solution Steps

In a titration, the endpoint is a critical point that indicates the completion of the reaction between the titrant and the substance being titrated. It is typically identified by a noticeable change, such as a color change in the indicator used.

Let's analyze the given options to determine which one correctly describes the endpoint in a titration:

• The indicator changes color: This is a common method to identify the endpoint. The color change signifies that the titration has reached a point where the amount of titrant is stoichiometrically equivalent to the amount of substance in the solution.
• The pH equals the pKa: This condition is specific to a half-equivalence point in a weak acid-strong base titration, not necessarily the endpoint.
• Moles of acid equals moles of base: This describes the equivalence point, which is the theoretical completion of the reaction. The endpoint is often very close to the equivalence point but is practically identified by the indicator's color change.

The endpoint in a titration is most commonly identified by the change in color of the indicator, which signals that the titration is complete.

Final Answer