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Paper Chromatography and Separating immiscible liquids. E. Haniff. Objectives. Separate a mixture of different solutions using a given solvent (by difference of solubilities ) Separate a mixture of immiscible liquids. What are immiscible liquids?. - PowerPoint PPT Presentation
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Paper Chromatography and Separating immiscible liquidsE. Haniff
Objectives• Separate a mixture of different
solutions using a given solvent (by difference of solubilities)
• Separate a mixture of immiscible liquids
What are immiscible liquids?• Immiscible liquids are two liquids
which cannot be dissolved in one another
• They form two distinct layers
Separating immiscible liquids
Title: Separation of two immiscible liquids• Aim: To separate a mixture of oil
and water• Apparatus and materials:
Separating funnel with tap, water, oil and 3 containers
Diagram:
Method• The apparatus was set up as shown
in the diagram• The denser liquid at the bottom of the
separating funnel was withdrawn through the tap and collected in a container
• The container was then replaced with another and a small quantity of liquid was withdrawn (a mixture of the two right after the denser liquid was withdrawn
Method continued…
• The container was then replaced again and the less dense liquid was allowed to run out and was collected.
• Observations were noted
Observations
• Two separate layers were formed in the separating funnel.
• The oil was seen at the top layer and the water at the bottom layer
Discussion• The separation of two immiscible
liquids is based on the principle that the two liquids do not mix and form two distinct layers
• The less dense liquid was the oil, which formed the top layer
• The denser liquid was the water which formed the bottom layer and was withdrawn first, allowing the separation of the two liquids
Conclusion• The mixture of oil and water was
separated using a separating funnel• Oil and water are immiscible liquids
because they do not dissolve one another
Application….• The principle of immiscibility of liquids
in some solvents is used in solvent extraction
• Solvent extraction is used to separate a component from a mixture by using two solvents.
• Two conditions have to be met:The component must be more soluble
in one solvent than in the otherThe two solvents must be immiscible
For example…pg 75• To compare the solubility of iodine in
two solvents• Iodine is dissolved in water• The water is mixed with 1,1,1-
trichloroethane• The iodine goes into this solvent and
the water can be drained off in a separating funnel
Another example
Uses of solvent extraction• Good for removing organic molecules
from water• For example caffeine from tea or
coffee.• Caffeine is an organic compound
which is more soluble in an organic solvent which is immiscible with water.(Dichloromethane)
Title: Paper Chromatography• Aim: To separate the components
of screened methyl orange• Apparatus and materials: filter
paper, beaker, capillary tube, test tube, screened methyl orange
Diagram:
Method:• To a strip of filter paper, a capillary
tube was used to place a small drop of methyl orange, close to the base of the paper
• A small volume of water was placed in a test tube or beaker
• The strip of filter paper was suspended so that it barely touched the solvent
Method:• It was left to stand for a while • Observations were recorded
Observations
• The liquid moved up the filter paper• Distinct colours could be seen• The colour that moved the furthest up
the filter paper was…….
Observations
Discussion• Chromatography is a technique that
uses a stationary phase and a mobile phase
• The stationary phase is the filter paper in paper chromatography
• The mobile phase is the solvent that moves up the paper
• Chromatography can be used to separate minute quantities of substances.
Discussion• Separation of the different
components occurs because each substance is soluble to different extents in the chosen solvent (the mobile phase)
• The more soluble component travels the furthest up the filter paper and the least soluble remains closer to the base
• Two colours were seen in screened methyl orange: two dyes a blue and a yellow
Conclusion• Screened methyl orange contains two
components: a blue dye and a yellow dye
• The more soluble component appeared blue in colour
• The blue dye was more soluble in water
Applications of chromatography
• Testing for trace contaminants in the environment
• Monitoring water quality and air quality
• Analyzing pure samples for trace contaminants (pharmaceutical industry)
• Quality control in food industry