What appearance of an acidic analyte solution containing phenolphthalein indicates the endpoint of titration with a basic solution?

The endpoint of a titration between an acidic analyte solution containing phenolphthalein and a basic solution is indicated by a color change in the solution. Phenolphthalein is a pH indicator that changes color depending on the pH of the solution it is in.

In an acidic or neutral solution, phenolphthalein is colorless. However, when the solution becomes slightly basic (pH greater than 8.2), phenolphthalein will turn a fuchsia or pink color.

So, during a titration, as the basic solution is added to the acidic solution, the solution will eventually reach a point where it is no longer acidic but becomes slightly basic. This is the endpoint of the titration, and it is indicated by the solution changing from colorless to pink.

Here are the steps:

1. Start with the acidic analyte solution containing phenolphthalein. At this point, the solution is colorless.

2. Begin adding the basic solution to the acidic solution slowly, while stirring the solution to ensure it is well mixed.

3. Continue adding the basic solution until the color of the solution changes from colorless to pink. This color change indicates that the solution has become slightly basic.

4. The point at which this color change occurs is the endpoint of the titration.