Answer to Question #107443 in Organic Chemistry for Jane

Question

during recrystallization:

1) why activated charcoal is used?
2) why solution should not immediately placed in ice bath after hot filtration/
3) why not 50% of boiling solvent was added to solute to prevent premature crystalization?
4) why not large amount of charcoal is used?

Answer 1

1) Activated charcoal adsorbs impurities from the solution

2) Because in case of fast cooling of the solution crystalss will be smaller and more dirty

3) The more solvent you will add the more substance will stay in solution, and so the yield will be lower.

4) Because charcoal can adsorb the substance being recristallized, and not just impurities, and therefore can reduce the yield.