Question

How would the calculated molarity for NaOH be affected (higher, lower, or no change) if the following procedural errors occurred? Explain why in each case.

a. While pipetting the H2SO4 solution, several drops of H2SO4 drip out of your pipet onto the bench top and miss the Erlenmeyer flask.

NaOH molarity (circle one): high or low

Why?

b. The buret tip is not filled with NaOH at the beginning of the titration.

NaOH molarity (circle one) : high or low

Why?

Answer 1

a)

As some acid is lost, the calculated molarity is lower than expected, and the actual no.of moles present in acid will be lower than the pipetted volume.

So , the volume of NaOH required to react the equivalence point will be less than the required volume. In turn molarity of NaOH computed will be less than expected.

b)

The calculated molarity will be higher than expected as the burette tip was not filled completely. So the volume of NaoH required will be higher than expected value thus molarity will be high.