Q1: How would each of the following problems in the standardization of KMnO₄ affect the measured value of the KMnO₄ molarity (make it larger, smaller, both larger and smaller or have no effect).  Explain why.  Specify if the problem that occurs in each measurement affects mostly precision or accuracy of the measurement.

Answers:  larger molarity of KMnO₄

i) overshooting the end point:Increasing molarity of KMnO₄

Effect:

Explanation:

ii) the primary standard dissolved in larger than prescribed amount of water: 

Effect: No effect

Explanation: If the amount of water is less than prescribed, then the molarity of the solution will stay the same. This is because the same amount of KMnO₄ would be required to titrate the same amount of Na₂C₂O₄ in the solution. This does not affect precision or accuracy.

iii) wet primary standard:

Effect:  smaller molarity of KMnO₄

Explanation:A wet primary standard affects the concentration of Na₂C₂O₄, since the larger amount of Na₂C₂O₄wouldrequire more volume of KMnO₄.This would result in an increase of volume and decrease in molar weight.The decreased molarity of KMnO­4 would affect the accuracy of the measurement, as this error affects the concentration of the Na₂C₂O₄ and cannot be attributed to randomness.

iv) a dirty buret (drops of KMnO4 remain on a buret wall)

Effect:  Smaller molarity of KMnO₄

Explanation:A dirty buret wouldincrease the volume of KMnO₄ required for titration due to impurities. This would result in larger final volume measured.This would affect the accuracy of the measurement.

v) few drops of titrant didn't make it into the solution:

Effect:  smaller molarity of KMnO₄

Explanation:

If a few drops of titrant didn't make it into the solution, then the molarity will decrease due to the greater recorded volume used. It would result in decreased accuracy because this would result in a value farther from the true value of KMnO₄. It cannot be attributed to randomness.

vi) buretreading errors:

Effect: Either larger or smaller molarity of KMnO₄

Explanation:If read incorrectly, then the volume of KMnO₄will be inaccurate. It would result in an increase or decrease in molarity, depending on the reading error. Because reading error is not duplicable and the error is random rather than systematic, the precision will be mostly affected by this type of error.