Types of distillation and examples

1. Ena Haniff
Simple distillation and fractional
distillation

2. Introduction
 If I have a solution of copper sulphate, how might
we obtain the solvent?
 Would evaporation be a suitable technique?

3. Introduction
 In this lab session we are going to use a
separation technique that retrieves the solvent
from a solution
 We are also going to separate two MISCIBLE
liquids

4. Simple distillation
The apparatus is set up as shown below

5. The process
 The solution is heated
 What happens at this point?
 The vapour rises up the flask and enters
the condenser
 What do you think will happen to the
remaining solution in the flask?
 It will become more concentrated

6. The process
 The vapour in the condenser is cooled by
the flow of cold water in the outer jacket
 What effect does this have on the vapour?
 It causes the vapour to condense
 What is the liquid that is collected in the
receiving flask?
 The distillate, pure water

7. Aim: To separate a solution and
obtain the solvent
 Apparatus and materials:
• Thermometer,
• condenser,
• distillation flask,
• bunsen burner,
• copper sulphate solution,
• retort stand,
• receiving flask

8. Diagram

9. Method
 The apparatus was set up as shown in the diagram
 Observations were noted
Observations
 The solution started to boil at …..°C.
 Colourless vapour evaporated and formed drops of clear
liquid in the condenser.
 The drops ran down the condenser and were collected in
the receiving flask.
 The solution in the flask became darker blue in colour
 The solid eventually remained in the round bottom flask.

10. Simple distillation: Discussion
• Simple distillation is used to separate and retain
the solvent from a solution eg. To obtain water
from sea water.
• The method is based on the principle that the
solvent is more volatile than the solute and
evaporates (volatile measures the tendency to
vaporise)
• The solid remains in the flask and is called the
residue
• The distilled product is called the distillate

11. Simple distillation: Discussion
• During the process as heat is applied, the water
began to boil off and became water vapour which
rose up to the top of the flask
• The water vapour entered the condenser where
cold water from the inlet caused the water to
condense and run off into the receiving flask
• As the water is removed from the solution, the
solution got deeper in colour because it became
more concentrated.

12. Simple distillation: Conclusion
• The separation technique of simple distillation
was effective in retrieving the solvent from a
solution
• The distillate obtained is water
• Solution pure solvent (as vapour) pure
solvent (as liquid)

13. Aim: To separate a mixture of
miscible liquids
 Apparatus and materials:
• Fractionating column
• Thermometer,
• condenser,
• 3 distillation flasks,
• bunsen burner,
• Solution (alcohol and water),
• retort stand,

14. Diagram

15. Method
 The apparatus was set up as shown in the diagram
 Observations were noted
Observations
 The solution started to boil at …..°C.
 Vapours evaporated from the solution and travelled up the
fractionating column
 The vapours cooled and condensed in the column
 Clear, colourless drops condensed and ran down the condenser
into the receiving flask where they were collected
 After the first fraction was obtained, a sharp rise in
temperature was noted and a second fraction was collected
then
 The temperature then remained at 100°C and a third fraction
was collected containing a colourless liquid.

16. Fractional distillation: Discussion
• Fractional distillation is used to separate two
miscible liquids (liquids that are readily
dissolved in one another)
• This technique is based on the principle that
one of the liquids is more volatile than the
other (has a lower boiling point and vaporises
first)
• The boiling point of ethanol is 78° and pure
water is 100°

17. Fractional distillation: Discussion
• As the mixture of liquids was heated, the vapours
rose up the fractionating column and continually
condensed and vaporised, with the lower boiling
point liquid (the more volatile one), rising to the
higher part of the column
• This liquid condensed first and was collected as
the first fraction
• The thermometer measures the temperature of
the vapour at the top of the column and
indicated what liquid is driven off

18. Fractional distillation: Discussion
• When the temperature reaches the boiling point
of the second liquid, that is then distilled into
another container.
• Fractional distillation is used on an industrial
scale in the separation of liquid air and the
refining of crude oil.

19. Conclusion
 A mixture of miscible liquids was separated by
the method of fractional distillation
 The first fraction collected was alcohol and the
third fraction was water
 The second fraction collected a mixture of two
fractions.

20. Applications of fractional distillation
 Can you suggest an application of fractional
distillation?
 Separation of crude oil