Distillation

Raoult's Law

Law which states the vapor pressure of a solution is directly proportional to the mole fraction of solvent present

Azeotropes

Mixtures with a fixed composition that cannot be altered by simple or fractional distillation; has a constant bp; behaves just like that of a pure substance

Use a fractionating column

Two liquids have boiling points which are less than 20 °C apart. How can a simple distillation be modified to improve the separation?

Vacuum distillation

Type of distillation carried out under reduced pressure; used for compounds that decompose at boiling points or are sensitive to oxidation

Simple distillation

Type of distillation that is not a complete distillation; used when boiling point difference between the two liquids is large (75C or more)

Fractional distillation

Type of distillation that is used when the boiling point difference between the two liquids is small; is a series of continuous distillations

Steam distillation

Type of distillation used with immiscible liquids

Maximum boiling

Azeotrope with boiling point above the pure boiling points of both liquids

Minimum boiling

Azeotrope with boiling point below the pure boiling points of both liquids

It allows you to distil liquids that may degrade when heated above a certain temperature

What is the key benefit of using vacuum distillation?

Hold up

What is the unrecoverable distillate that wets the column packing?

A few drops per minute

What rate should the liquid come across in a fractional distillation?

a & b

Which of the following is an appropriate use for distillation apparatus? More than one answer may be correct. a) To remove a liquid product from a reaction mixture. b)To measure a boiling point of a liquid. c)To remove a liquid from a reaction mixture, allowing collection of an insoluble product.

a & c

Which of the following is an appropriate use for distillation apparatus? More than one answer may be correct. a)To remove a liquid product from a reaction mixture. b)To remove a liquid from a reaction mixture, allowing collection of an insoluble product. C)To measure a boiling point of a liquid.

Simple distillation

You are required to separate a mixture of two solvents. One has a boiling point of 45°C, and the other has a boiling point of 120°C. Which is the most appropriate type of distillation to use?