CHE 211 Study Guide - Midterm Guide: Metal Foam, Polytetrafluoroethylene, Theoretical Plate
Organic Chemistry 2 – Chemical Purification & Separation
Fractional Distillation
• Fractional distillation is the process of repeated vaporizations and condensations This
allows us to separate components of a mixture by exploiting the differences in vapor
pressure of the component
• Takes advantage of the vapor pressure differences of the components of the mixture
• Fractionating column is inserted between the distilling flask and the distillation head;
This is inserted in the simple distillation apparatus, which can be seen below
The use of a fractional column gives us a greater surface area over which many
vaporization/condensations cycles can occur
As the vapor travels up the column, it cools, condenses into a liquid and the
vaporizes again when it comes in contact with hotter vapors rising from below
This process is repeated many times until the vapor finally reaches the
condenser and is cooled and condensed for the last time
If the fractionating column is efficient, the vapour that finally reaches the
condenser will be composed entirely of the component will the lower boiling
point --> the efficiency of the fractionating column can be expressed by the
number of theoretical plates it contains (a theoretical plate is one
vaporization/condensation cycle --> this means that a theoretical plate is
equivalent to one distillation)
A distillation apparatus that has the efficiency of 2 theoretical plates is
equivalent to 2 simple distillations;
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