Question

Describe and explain the possible effect on your results of the following experimental errors or violations. In each case, specify the component(s) whose percentage(s) would be too high or too low

(a) After adding dichloromethane to Panacetin, you didn't stir or shake the mixture long enough

(b) During the NaHCO3 extraction, you failed to mix the aqueous and organic layers thoroghly

(c) You mistakenly extracted the dichloromethane solution with 5% HCl rather than 5% NaHCO3

(d) Instead of using pH paper, you neutralized the NaHCO3 solution to pH 7 using lithmus paper

Answer 1

a) This would result in incomplete dissolution of the panacetin mixture, and you would lose some of the solid analytes when the solution was filtered (the undissolved analytes would be filtered out with the starch). The recovered amounts would be lower than they should be, so the final percentages would be low.

b) if we didnt mix the aqueous and organic layers thoroghly we loss some quantity of NaHCO₃

C) if u used the 5% HCl that would protonate the aspirin and keep it in the organic phase soln making the aspirin acetylsalicylic acid. So i guess thats why u used bicarbonate (to precipitate the base form = acetylsalicylate)
D)   at ph7 theNaHCO3 wouldnt be able to act as a base and extract a proton from the aspirin because at ph7 it would be protonated itself, so it wouldnt be able to react with the aspirin