Separating Mixtures

1. SEPARATING MATERIALS
Mixtures of materials can be separated using
different methods.
The method used depends upon the nature of
the mixture to be separated.

2. Sieves are frames with a wire mesh
stretched across the frame.
The mesh has lots of holes in it.
Holes in the mesh

3. Filtering
The liquid water passes easily through the
tiny holes in the filter paper but the solid
specks of gold are too big to pass through
the same holes.
This means that the gold is collected in the
filter paper and the water is collected in the
measuring cylinder/

4. Before After

5. Having separated out the solid
particles by sieving or filtering,
there may be substances dissolved
the the filtered liquid – the filtrate.
To separate the water from the
dissolved substances a different
method is needed.

6. EVAPORATION
When liquid changes to gas, this is called evaporation.
This can be used to separate solids from liquids and
also dissolved solids from the solvent.
Evaporating water

7. Hot Coffee
Water grains
What happens to the solid coffee grains when
they are put into hot water? Explain your answer

8. Dissolving
Some solids like salt when put into water can
be seen at first but gradually get smaller and
will eventually disappear.
The water breaks up the salt into smaller and
smaller particles which move around in the
water, until they are so small that they cannot
be seen - the salt has Dissolved.
The liquid is now called a Solution of salt water.
Other solids like Chalk are not broken down
by water and so do not dissolve but stay solid,
as a Suspension in the water.

9. The solid coffee
grains dissolve in the
hot water. There is
now a solution of
coffee in the cup. The
coffee is now a liquid.
What would happen if the cup of coffee was
left on a hot radiator for a few hours? What
sort of change is this an example of?
N

10. DISTILLATION
This is a method used to separate liquid
mixtures into their different component parts.
A liquid mixture is heated in a container
such as a test tube or flask until the liquid
boils. The gas is passed through a delivery
tube into a condenser. This cools the gas
causing it to condense. The resulting pure
liquid is collected. The other part of the
mixture is left in the container.

11. Separating a mixture of water and ink by
Distillation
B
C
Water
+ ink
Beaker
A
Heat Water D
Explain what is happening at each stage A - D N

12. Separating a mixture of water and ink by
Distillation
B evaporation of water
C – condensation of water
Water
+ ink
Beaker
A Boiling water
Heat D pure water collected
Water

13. Distilling Muddy Water to get Clean Water
Thermometer
Cold water
in
Flask Condenser
Cold water
Muddy out
water
Heat Beaker

14. Distilling Muddy Water to get Pure Water
Label the above diagram and explain in detail what
is happening to the muddy water to get pure water. N

15. CHROMATOGRAPHY
Some solids dissolved in a solvent can be
separated by a method called Chromatography.
Ink pens such as felt tips can often contain a
number of different dyes. With many coloured
inks water can be used as a solvent to separate
these dyes. In this way inks ( and other mixtures)
can be tested to see if they are pure or made up
from a number of different dyes mixed together.

16. CHROMATOGRAPHY
There are two reasons for the separation
by chromatography, of the different
chemicals in a mixture.
1. Some chemicals will dissolve in the solvent
more quickly, the better they dissolve the further
they travel.
2. The paper absorbs different chemicals to
different extents.

17. CHROMATOGRAPHY
A spot of ink in the A dropper pipette is
centre or some used to add drops of
Chromatography water to the spot of
paper ink
The drops of water causes the dried ink spot to spread outwards.
As the ink is made up from different colours that travel at
different rates through the paper, the ink is separated into the
different colours forming the cultured rings.

18. CHROMATOGRAPHY
A spot of ink in the A dropper pipette is
centre or some used to add drops of
Chromatography water to the spot of
paper ink
Explain what is happening to the dried ink spot
in the second diagram.
N

19. CHROMATOGRAPHY
Red Yellow Blue 1 2 3 4
Pure Inks Unknown Inks
N

20. SOLUBILITY
If a substance dissolves it is said to be
Soluble. How hard it is to dissolve it or how
easy it is, is known as its’ Solubility.
Solubility can be affected by different
factors, one of which is the Temperature of
the Solvent which is dissolving the Solute
(the substance being dissolved).