Give reasons for each of the following experimental techniques used in crystallization. (a) A hot ...

(a) Solvent is lost by evaporation and premature crystallization can occur. In addition, some
of the compound wil be also lost by adsorption on the filter paper.
(b) A vacuum will be created in a tightly stoppered flask as the solvent vapors cool.
(c) If the aspirator is turned off while the system is still under vacuum, water will be sucked
into the filter assembly.
(d) A very volatile solvent will vaporize during the vacuum filtration causing the compound
to precipitate. Also the rapid evaporation of the solvent on the filtered crystals prior to
their being washed wil result in impurities in the solvent being deposited on them.