The question is incomplete; the complete question is;
Before running a titration, you calculate the expected endpoint. However, when performing the experiment, you pass the expected endpoint with no visible color change. What is the most likely problem with the titration set- up? Select one
a) There was an air bubble in the burette tip.
b) There is not enough indicator in the analyte.
c) The burette tip is leaking titrant into the analyte.
d) The analyte solution is being stirred too quickly
Answer:
a) There was an air bubble in the burette tip.
Explanation:
Titration involves the determination of the concentration of a solution by measuring the volumes of reactants used in the reaction. The concentration of one of the species must be known while the concentration of the other specie is to be determined by the volumetric analysis.
However, if there are air bubbles at the tip of the burette, this will cause less volume of titrant to be delivered from the burette than expected. Hence, the analyst may think that a certain volume of titrant has been delivered while in reality, a lesser volume was actually delivered due to the air bubbles present. Hence, the analyst may pass the expected endpoint without any colour change because of this problem.
From the available options to the question:
a) There was an air bubble in the burette tip.
b) There is not enough indicator in the analyte.
c) The burette tip is leaking titrant into the analyte.
d) The analyte solution is being stirred too quickly
The most likely problem with the titration setup that could make one to pass the expected endpoint with no visible color change would be if there is not enough indicator in the analyte. The correct option would be B.
A suitable quantity (in drops) of the indicator should be added to the analyte in the conical flask before carrying out a titration. The color of indicators changes quickly near their pKa.
If too few drops of the indicator is used, the color change will be too faint to be obvious and the endpoint will be exceeded. If too many drops of the indicator is used, the final pH of the reaction would be affected and the titer value will be inaccurate.
In this case, the expected endpoint has been exceeded without any color change. The most likely problem would, therefore, be that there is not enough indicator in the analyte.
More on indicators can be found here: https://brainly.com/question/4050911
