Lab Questions 1. Suppose you dispense titrant until a very, very faint pink colo

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Lab Questions 1. Suppose you dispense titrant until a very, very faint pink color persists and does not disappear. Explain whether or not more titrant is needed, and how you would proceed. 2. An air bubble is inadvertently left in the NaOH buret tip prior to a titration, and it exits during the titration. Explain how this affects the volume measurement and concentration calculation for NaOH in part A 3. Suppose some titrant liquid clings to the wall of the buret, and does not drain down during the titration. Explain how this affects the level of the meniscus and the final volume measurement. 4. Suppose one group left the cap off the container of slightly hygroscopic KHP before your group obtained it. Explain how and why your calculations of KHP, NaOH, and acid moles may be different from the actual moles of each. s. Suppose you rinse the analyte flask with boiled, deionized water during the titration as directed by the procedure, but you use a lot of water. Explain if, and how, this affects your moles of acid and base in the flask, and your concentration calculations.

Explanation / Answer

1. This is the end point of the titration and you need not require any more titrant. At the end point of a titration, a persistent light pink color denotes end point.

2. The presence of an air bubble in the burette containing NaOH, increases the volume of the fluid. Molarity equals number of moles per volume, and as a result of this, concentration calculated has a smaller value than its actual value.

3. As some liquid clinges to the wall, and does not drain down during titration, the level of meniscus is lower than the actual value of the liquid present. As a result, the measured volume is more than what it should be. When we calculate:-

Final volume= Final Reading - Initial Reading,

we get a value that is higher than the actual value. This acts as a source of error in titration.

4. As the previous group left the cap off the container, the KHP might absorb some amount of moisture in the air, and as a result, has an increase in volume. Thus, due to this increased value of volume V, acid moles calculated are different from the actual moles.

5. Usage of excess water does not have any effect on the titration procedure, as long as the water is completely rinsed out( no residual water is left behind in the burette), and the burette is rinsed with the titrant once.

Thanks for reading :)

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