3. How would the following errors affect the molar mass determination (oo high,

Question

3. How would the following errors affect the molar mass determination (oo high, too low, or no effect) in g errors affect the molar mass determination (too high, too low, or no effect) in the second part of this lab? Explain your answers. (a) After the a Aferae burete h ben sii tNaOlH solution and the initial olume of base has been recorded, a drop of NaOH solution falls from the tip of the funnel into the burette as the funnel was being removed. The titration of the unknown diprotic acid then proceeds. (b You standandized NaO olnin is lot sahd nainow (b) Your standardized NaOH solution is left standing in air for a week, because the cap was left off its plastic con tainer, and then used for the titration of the unknown acid. Assume that there is minimal to no loss in the total volume of the solution due to evaporation over the week.

Explanation / Answer

a) in the first case, it will have a low effect, basically because we already recorded the volume of the NaOH, and the escape of that drop would not affect this much to the final determination. Tis drop is only 0.05 mL and at the end when you are calculating the moles, basing on the concentration and volume used, there will be a little amount different but below the real one and not too much.

b) In this case, it will be too high, because the NaOH solution will be impure, and it can drop a false value of volume and concentration would be lower than the original, so the moles would be higher and molar mass higher too.

c) You already reach the endpoint, and it suppose to be recorded, so that drop hanging still, will have no effect in the molar mass determination.

Hope this helps

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