Explains the various separation techniques.

1. Text by Mrs Teo
Video clips taken from school video repository

2. Instructions
1. You have learnt that a mixture is made up
of components not chemically combined
together.
Thus the components can be separated by
several methods.
2. Go through this lesson package on the
various separation techniques.
3. Follow up by reading your textbook.

3. 1. A mixture is made up of components not
chemically combined together, e.g. ink, fizzy
drinks, mineral water, crude oil, air
2. The components of a mixture can be
separated by several methods or techniques.
3. Each separation technique makes use of
differences in the physical properties of the
components

4. The Different Separation Techniques are
as follows:
• Magnetic attraction
• Filtration
• Evaporation
• Crystallisation
• Distillation
• Chromatography

5. Magnetic Attraction
• used to separate magnetic
materials, e.g. iron, steel, nickel,
cobalt from non-magnetic ones in a
mixture
e.g. separating iron filings from
sulphur powder

6. Applications of Magnetic Attraction
1.Electromagnets are
used to remove
steel and iron scrap
at the junk-yard.
2. In hospitals, magnets are often used
to remove iron splinters from a
patient’s eyes.

7. Using a Separating Funnel
• can be used to separate two
immiscible liquids, such as oil
and water
http://vle.hci.edu.sg/chemistry/beijing/expt%20techniques/lesson5.html

8. Filtration
• used to separate
(i) an insoluble solid from a liquid in a solid-liquid
mixture
e.g. sand from a mixture of sand and water
sand)
(water that passes
through filter paper)

9. Filtration
• (ii) used to separate an insoluble solid from
a soluble solid
e.g. insoluble calcium carbonate from
soluble copper(II) sulphate

10. Filtration
• insoluble solid that remains on the
filter paper - residue
• liquid that passes through- filtrate
(filtrate can be water, any other
solvent, or a solution)

11. Applications of Filtration
• hair in our nostrils
trap the dust particles that we breathe in
and allow only clean air to pass through
• air filters in air conditioners
remove solid impurities from air
• oil and air filters in cars
remove solid impurities found in engine
oil and air

12. Evaporation to dryness
• used to separate a dissolved solid
(solute) that does not decompose on
heating from a solution,
solution,
e.g. common salt from a salt solution

13. Procedure of Evaporating a Solution
1. Pour the solution into an evaporating dish.
2. Heat the solution to dryness to evaporate
away the solvent, leaving behind the solute.
3. Make the Bunsen flame smaller when almost
all the solvent has been evaporated away to
reduce spitting.

14. Applications of Evaporation
• drying wet clothes
• drying hair with a hair-dryer
hair-dryer
• obtaining common salt from the sea

15. Crystallisation
• process to obtain a solid that
decomposes on heating from its
solution
e.g. sugar crystals from sugar
solution and copper(II) sulfate
crystals from copper(II) sulfate
solution

16. Procedure of Crystallisation
1. Pour the solution, e.g. copper (II) sulfate
solution, into an evaporating dish.
2. Heat the solution to evaporate away the solvent
until some solid starts to appear or a saturated
solution is obtained.
3. Leave the solution to cool.
4. On cooling crystals of the solute that can no
longer disssolve in the solution will be deposited
as crystals.
5. Filter the mixture to collect the crystals which
will be the residue.

17. Simple Distillation
• process used to separate a pure liquid
(solvent) from a solid-liquid solution
e.g. pure water can be distilled from soft
drinks, sea-water, etc

18. Distillation

19. Simple Distillation
• solution boiled in distilling flask and vapour/steam cooled
and condensed in a Liebig condenser
• condenser consists of jacket of cold water with coldest
water entering bottom of jacket and circulating out
through the top ensuring that coldest part of condenser
is just before the vapour escapes and that the jacket is
completing full of water
• condensed solvent – distillate
• all impurities left in distilling flask
• anti-bumping granules/boiling chips/beads-ensure even
boiling

20. Fractional Distillation
• process can be used to separate
miscible liquids with different boiling
points
• liquid with lower boiling point will
vaporise first
e.g. to separate alcohol and water

21. Fractional Distillation

22. Industrial Applications of Fractional Distillation
• oil refineries
- separating the various components of
crude oil or petroleum

23. Industrial Applications of Fractional Distillation
•industries supplying
oxygen to hospitals,
shipyards, etc
– separating the
components of air

24. Paper Chromatography
• process used to separate the different
components in a liquid mixture
For example it can be used
1. to separate the different coloured
components that make up black ink
2. to detect tiny amounts of drugs or
certain other chemicals in urine samples

25. Paper Chromatography
1. Apply a small but concentrated
spot of the solution on a piece of
chromatography paper.
2. Suspend the chromatography
paper in a beaker or boiling tube of
solvent with the spot above the
level of the solvent.

26. Paper Chromatography
3. Separation takes place because
some components of the liquid
mixture travel at a faster pace
than other components on the
paper or any other absorbent
material.

27. Paper Chromatography
3. As the solvent travels up the
paper, the mixture is separated
into its respective components.
A chromatogram of the separated
components is obtained.
YouTube video clip

31. Applications
•analysing ink dyes for forgery cases
•analysing
•analysing food dyes to ensure that
•analysing
only permitted colourings are used
in foodstuffs
•checking whether pesticides on
vegetables exceed safe levels
•detecting trace levels of drugs in
•detecting
urine samples

32. Sublimation
- process by which a substance changes from solid
state to vapour state on heating
- e.g of substances which sublime
- iodine
- ammonium chloride
On heating, they do not melt. Iodine changes
into a beautiful violet vapour while ammonium
chloride changes into a white vapour.
They change back into solid crystals on cooling.

33. Sublimation
- process used to separate a solid
that sublimes from one that does
not
e.g. iodine or ammonium chloride
from common salt

34. Sublimation
When a mixture of a solid that sublimes
and a solid that does not is heated, the
solid that sublimes will turn into a vapour
and separates from the other solid which
remains in the container.

35. The End

36. ACE Suggestions
1. Production of whisky by distillation of barley mash

37. ACE Suggestions
2. Commercial Production of sodium chloride by:
(i) Mining
(ii) Evaporation of sea water