Separation Techniques:
Objectives:
- describe techniques for the separation of
mixtures, including simple distillation, fractional
distillation, filtration, crystallisation and paper
chromatography.
Outcomes:
• Be able to describe & explain distillation &
paper chromatography
• Be able to carry out chromatography to
separate dyes
Distillation:
• Distillation is a process that can be used to obtain a pure
liquid from another liquid or a solid. It works when the
substances have different boiling points.
• This is the sequence of events in distillation:
heating → evaporating → cooling → condensing
Fractional distillation
• Remember: Distillation is a process that can be
used to collect one pure liquid from a mixture of
substances.
• Fractional distillation takes advantage of the fact
that different liquids will have all different boiling
points and allows you to collect multiple pure
liquids
• heating → evaporating → cooling → condensing
Liebig
E.G:
How does fractional distillation work?
6 of 37
© Boardworks Ltd 2006
Fractional distillation of
air
Colder at the top
1. Air has to be
condensed into a
liquid. This
happens at 200oC.
2. This is done by
compressing or
squashing the air
and the use of
cold water.
3. At -200oC
carbon dioxide
and water are
solids so can be
easily taken out.
Warmer at the
bottom
4. Nitrogen boils at
-196oC so it can be
removed from the
top of the column
as a gas.
5. At -185oC
oxygen is still a
liquid so can be
taken out the
bottom of the
column.
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Twig videos
Filtration - https://www.twig-world.com/experiment/chemical-filtration-4131/
Evaporation - https://www.twig-world.com/experiment/filtration-and-evaporation-4130/
Salt separating mixtures - https://www.twig-world.com/film/salt-separating-mixtures-1476/
Fractional distillation - https://www.twig-world.com/film/fractional-distillation-1371/
Distillation of ink - https://www.twig-world.com/experiment/distillation-of-ink-4129/
Chromatography - https://www.twig-world.com/search/?search=chromatography&search-btn=
Sublimation - https://www.twig-world.com/experiment/fire-extinguisher-sublimation-4128/
Centrifuge - https://www.youtube.com/watch?v=KEXWd3_fM94
Separation techniques:
Objectives:
- describe techniques for the separation of
mixtures
Objectives:
D: Be able to identify simple separation
techniques
A-C:
- Describe filtration and crystallisation and their
uses
Filtration & crystallisation:
• Filtration: separates a solid from a liquid
• Crystallisation: if a solid is dissolved in water it
can be recovered by evaporation or
crystallisation
• When a solution is heated, the liquid will start
to evaporate.
• When the solution becomes saturated, the
solute will begin to crystallise and will appear
in the solution
• So how would we carry out a practical to
separate sand, salt and water?
When you are done:
• Write a paragraph to describe this experiment.
Make sure all of the following words are used:
dissolve, solvent, filter, filtrate, evaporate,
solute, crystallise, crystal.