Concept Summary

Solubility-Based Methods

Distillation

Extraction  combines    two immiscible  liquids,    one of  which   easily  dissolves   the compound    of

interest.

The polar   (water) layer   is  called  the aqueous phase   and dissolves   compounds   with    hydrogen

bonding or  polarity.

The nonpolar    layer   is  called  the organic phase   and dissolves   nonpolar    compounds.

Extraction  is  carried out in  a   separatory  funnel. One phase   is  collected,  and the solvent is  then

evaporated.

Acid–base   properties  can be  used    to  increase    solubility.

A   wash    is  the reverse of  extraction, in  which   a   small   amount  of  solute  that    dissolves   impurities  is

run over    the compound    of  interest.

Filtration  isolates    a   solid   (residue)   from    a   liquid  (filtrate).

Gravity filtration  is  used    when    the product of  interest    is  in  the filtrate.   Hot solvent is  used    to

maintain    solubility.

Vacuum  filtration  is  used    when    the product of  interest    is  the solid.  A   vacuum  is  connected   to

the flask   to  pull    the solvent through more    quickly.

In  recrystallization,  the product is  dissolved   in  a   minimum amount  of  hot solvent.    If  the

impurities  are more    soluble,    the crystals    will    reform  while   the flask   cools,  excluding   the

impurities.

Distillation    separates   liquids according   to  differences in  their   boiling points; the liquid  with    the

lowest  boiling point   vaporizes   first   and is  collected   as  the distillate.

Simple  distillation    can be  used    if  the boiling points  are under   150°C   and are at  least   25°C    apart.