1.  Purpose of fractional distillation.   Most important method of separating liquids.


2.   Theory

         a)   review

                 i)   vapor pressure
                 ii)   definition of bp: P_A = P_ATM

         b)   2 component system

                 i)   ideal homogeneous mixture; bp = P_ATM = P_A + P_B

                 ii)   P_A = P^o_A X_A

                 iii)   P_B = P^o_B X_B

                 iv)   Y_A/Y_B = P_A/P_B = P^o_A X_A/P^o_B X_B    where Y = mole fraction

                 v)   this allows for construction of a vapor pressure phase diagram for distillation
                 vi)   explain curve - more volatile vs. less volatile
                 vii)  theoretical plate (step)
                         a)   each is a simple distillation, a vaporization and condensation

         c)   the process

                 i)    fractionating column allows for increase TPs
                 ii)    HETP
                 iii)   actually a series of equilibria
                 iv)   reflux ratio:   drops that condense in column/drops that return to flask

         d)   azeotropes - 2 liquids that act as one (this is a non ideal case)

                 i)   maximum boiling
                 ii)   minimum boiling

         e)   distillation under reduced pressure

                 i)    lower bp of sample via lowering of atmospheric pressure
                 ii)   high boiling liquids can be distilled without decomposition
                 iii)   fractionation not as effective