The use of good technique while doing this experiment is very important. Briefly
ID: 789287 • Letter: T
Question
The use of good technique while doing this experiment is very important. Briefly explain whether the following technique errors would result in a high or a low experimental determination of the molar concentration of CH3COOH om vinegar.
(1) A student uses the pipet bulb to blow the last of vinegar from the tip into the titration flask, after the pipet has drained.
(2) A student fails to clean the pipet first. After delivering the vinegar sample, the student notices a drop of vinegar clinging to the inner surface of the pipet.
(3) A student stops the titration when the pink persists throughout the solution for less than 10 sec
(4) After completing a titration a student notices that the buret is not clean. Droplets of NaOH solution are clinging to the inner surface of the burret.
Explanation / Answer
(1) one would expect an increaseed concentration due to the fact that the student added the "extra bit that was left" which is normally not added due to it being inconsistant.
(2) one would expect a decreased concentration due to the fact that some vinegar has been leftbehind in the pipet.
(3) one would expect a lower concentration of vinegar to be present due to the fact that the titration was not llowed to go to completion.
(4) one would expect a lower concentration because not all the NaOH reacted but the volume would indicate it had?
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