Separation of Mixtures Using Different Techniques
Separating funnel
To do this experiment we require: a separating funnel, stand with clamp, mixture of oil and
water, filter funnel, beakers.
Take a filter funnel and place it on the mouth of the separating funnel which is clamped
to a stand. Pour the mixture of oil and water into the
separating funnel through the filter funnel. Oil and water will appear as separate layers.
Remove the filter funnel from the separating funnel and close the separating funnel using
a lid. Take the separating funnel from the stand.
Invert the funnel and shake it gently and slowly open the stopcock of the funnel to
release the pressure inside the funnel. Place the separating funnel in the stand and
allow the two liquids to separate completely. (Oil forms the top layer and water forms the
bottom layer.) Take a beaker and place it below the separating
funnel. Open the stopcock of the separating funnel
and pour out the lower layer of water carefully onto the beaker. Close the stopcock as the
oil reaches the stopcock. Take another beaker and place it below the
separating funnel. Open stopcock and now collect oil from the
separating funnel. The immiscible liquids separate out in layers
depending on their densities. The denser liquid will fall to the bottom
forming the lower layer and the lighter liquid forms the top layer. Water is denser than oil.
Simple distillation
We require a mixture of acetone and distilled water, stand with clamp, heating mantle
porcelain chips. Take a mixture of acetone and distilled water
and pour it into a 250 ml RB flask (distillation flask).
Clamp the RB flask to a stand and place it in a heating mantle.
Take some porcelain chips using a spatula and put it into the RB flask to avoid bumping
while boiling. Connect a distilling head to the RB flask
and a thermometer adapter to the distilling head.
Insert a thermometer though the thermometer adapter.
Connect a water condenser to the outlet of the distilling head.
Connect a vacuum adapter to the water condenser Connect a 100 ml RB flask (receiver flask)
to the vacuum adapter. Take an ice bath and place the RB flask in
the ice bath. Connect a rubber tube between the tap and
the inlet of the condenser to allow the cold water to enter.
Connect another rubber tube to the outlet of the condenser to pour the hot water from
the condenser to the sink. Open the tap so that water flows through the
tube and fills the condenser and then comes out through the outlet.
Set the temperature of the heating mantle to 56°C and heat the mixture to boil.
At 56°C, acetone vaporizes and the vapours pass through the condenser and condensation
occurs. The acetone is collected in the receiver flask in the liquid form.
Water is left behind in the distillation flask. Simple distillation is used for the separation
of a mixture containing two miscible liquids that boil without decomposition and have sufficient
difference in their boiling points. Acetone boils at 56°C and water boils at
100°C.
Fractional distillation
We require a mixture of methanol and ethanol,stand with clamp,
heating mantle and porcelain chips.
Take a mixture of methanol and ethanol and
pour it into a 250 ml RB flask (distillation flask).
Clamp the RB flask to a stand and place it in a heating mantle.
Take some porcelain chips using a spatula and put it into the RB flask to avoid bumping
while boiling. Connect a fractionating column to the RB flask.
Connect a distilling head to the fractionating column and a thermometer adapter to the distilling
head. Insert a thermometer though the thermometer
adapter. Connect a water condenser to the outlet of
the distilling head.
Connect a vacuum adapter to the water condenser.
Connect a 100 ml RB flask (receiver flask) to the vacuum adapter.
Take an ice bath and place the RB flask in the ice bath.
Connect a rubber tube between the tap and the inlet of the condenser to allow the cold
water to enter. Connect another rubber tube to the outlet
of the condenser to pour the hot water from the condenser to the sink.
Open the tap so that water flows through the tube and fills the condenser and then comes
out through the outlet.
Set the temperature of the heating mantle
to 65°C and heat the mixture to boil. At 65°C, methanol vaporizes and the vapours
first rise through the fractionating column and pass through the condenser. Condensation
occurs and methanol is collected in the receiver flask in the liquid form.
Remove the RB flask containing methanol and connect a new RB flask to the vacuum adapter.
Again set the temperature of the heating mantle to 78°C and heat the contents of the RB flask.
At 78°C, ethanol vapourises and the vapours rise through the fractionating column and
pass through the condenser and condensation takes place and ethanol gets collected in
the receiver flask in the liquid form.
Fractional distillation is used for the separation of two or more miscible liquids
for which the difference in boiling points is less than 25K.
Centrifugation
We require milk, distilled water, centrifuge tubes, centrifuge machine
Take a centrifuge and fill 3/4th of it with milk.
Place the centrifuge tube in one of the holes of the rotor of the centrifuge tube.
Take another centrifuge tube and fill 3/4th of it with distilled water.
Place it opposite to the first centrifuge tube to balance the centrifuge machine.
Then close the centrifuge machine and centrifuge the milk for 2 minutes and then stop the machine.
Take the centrifuge tube containing milk from the machine and observe the changes.
The fat rises to the top resulting in a cream layer at the top and skim milk (plasma phase
of milk) at the bottom. The denser particles forced to the bottom
and the lighter particles stay at the top when spun rapidly.
Chromatography
We require a mixture of red and blue inks, distilled water, isopropyl alcohol, Whatman
filter paper strip (20 x 2 cm), capillary tube.
Take a Whatman filter paper strip (20 x2 cm). Draw a line with a pencil above 4 cm from
one end. Draw another line lengthwise from the centre
of the paper and name the point at which two lines intersect as P.
Take a capillary tube. Dip it into the beaker containing a mixture
of red and blue inks and take the mixture using the capillary tube.
Put a drop of the mixture of red and blue inks at the point P.
Allow it to dry in open air. Again take mixture of red and blue inks using
the capillary tube. Put another drop on the same spot and dry
it again so that the spot is rich in mixture. Take 5 ml of distilled water in a measuring
cylinder and pour it into a chromatographic chamber.
Then take 5 ml of isopropyl alcohol in a measuring cylinder.
Pour it into the chromatographic chamber containing distilled water.
Mix the contents of the chromatographic chamber using a glass rod. This mixture is used as
the solvent. Take the filter paper and suspend the filter
paper vertically in the chromatographic chamber containing solvent in such a way that the
pencil line remains about 2 cm above the solvent level.
Close the chamber and keep it undisturbed for some time.
Notice the rise in solvent along with the mixture of red and blue inks.
When the solvent has risen about 15 cm, you will notice two different spots of blue and
red colours on the filter paper. Take the filter paper out of the chamber and
mark the distance that the solvent has raised on the paper with a pencil. This is called
the solvent front. Dry the paper and put pencil marks in the
centre of the blue and red spots. Measure the distance of the solvent front
from the original line and the distance of the two spots from the original line.
Calculate the Rf values of the blue and red inks by using the formula.
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