【Daily Question】Chemical Analysis Edition, 3/24/2021
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This post was last edited by zjp on 2021-3-24 08:06. Multiple-choice question: Regarding the indirect iodometric method for determining reducing substances, which of the following statements are correct? （ ） A. The solution being titrated should be neutral or slightly acidic. B. There should be an appropriate excess of KI in the solution being titrated. C. The indicator is added near the endpoint, and at the exact endpoint the blue color of the solution being titrated disappears. D. The titration rate can be increased appropriately, and the shaking of the solution being titrated should also be intensified simultaneously. E. Cu2+ ions present in the solution being titrated have no effect on the determination. Answers: AB
Option C in the question: The indicator is added near the endpoint, and at the titration endpoint, the blue color of the solution being titrated disappears exactly. The first half of this description is absolutely correct; in practical work, the titration endpoint is also reached when the blue color disappears. Generally, with this indirect iodimetry method, the color does not revert quickly at the endpoint, so it can be said that the description in option C is also correct.
This post was last edited by zxy0907 on 2021-3-25 20:15 AB