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Unit 4: laboratory techniques and their applications. Learning aim C: explore manufacturing techniques and testing methods for an organic solid.$10.80
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Unit 4 - Laboratory Techniques and their Application
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Sarah Hill – 175220 Unit 4
Unit 4: laboratory techniques and their applications. Learning aim C:
explore manufacturing techniques and testing methods for an
organic solid.
Introduction:
In this report I have correctly prepared and tested the purity of an organic solid and then
will be drawing up conclusions. I will be describing the industrial manufacture and testing of
an organic solid, then I will be demonstrating the skilful application of techniques in
preparing and testing the purity of an organic solid and will draw up conclusions. I will then
be comparing the laboratory and industrial manufacture testing of an organic solid. Finally, I
will be analysing the factors affecting the yield and purity of an organic solid in the
laboratory and their relevance to its industrial manufacture.
P5/M4 –
Organic compounds of various kinds are found in all kinds of living organisms, the physical
remains as well as their waste products. Many organic solids are man-made.
The method that we completed has 2 parts, part 1 which is the preparation, and then part 2
is the purification.
Part 1 starts by weighting out the salicylic acid into a conical flask, making sure to note the
weight of the salicylic acid. Then place the ethanoic anhydride into a measuring cylinder and
then adding this into the conical flask and swirl the contents to make sure everything is
incorporated. This is done to make sure everything is incorporated. Then add 5 drops of the
concentrated sulfuric acid to the conical flask and swirl the mixture ensuring thorough
mixing. Adding sulfuric acid is used as a catalyst which will speed up the reaction. Warm the
flask over a bunsen burner for about 20 minutes, to about 60°C. this mixture should not go
above 65°C. Next allow the flask to cool and pour its contents into the water in a beaker and
stir thoroughly to precipitate the solid, then filter the aspirin under reduced pressure but
avoiding skin contact. We added the mixture to a flask that’s cooled to stop the reaction.
Adding this allows the aspirin to come out of the solution allowing this to stop the solution.
The extraction of the aspirin gets rid of the liquid quickly and gets the crystals and also the
unreacted solution filtered, which ensures you have the aspirin left and anything else.
Part 2 is the purification steps this is done by putting the ethanol into a boiling tube. Then
prepare a beaker half-filled with hot water at the temperature of approximately 75°C. The
beaker must not exceed 78°C as this is the boiling point of ethanol and we do not want this
to melt. Then use a spatula to add the crude aspirin to the boiling tube and place the boiling
tube into the beaker of boiling water, this is to get rid of the other impurities by re-
dissolving them and leaving the aspirin as crystals. Pour the hot solution into some water in
a conical flask. If a solid separates at this stage gently warm the contents in a water bath
until the solution is complete. Then allow the conical flask to cool slowly and white needles
of aspirin begin to separate. Allowing the cooling of the conical flask allows the crystals of
the aspirin to reform. If no crystals have formed after the solution has cooled to room
temperature, you may need to scratch the insides of the flask with a glass stirring rod to
obtain the crystals, and then cool the whole mixture in a cooling bath. Then filter off the
purified solid under reduced pressure and allow this to dry on filter paper. This is done so
the water is dried out and then the pure aspirin is left on the filter paper; this is so when it is
, Sarah Hill – 175220 Unit 4
weighted compared to the starting weight, we can see the comparison between starting
weight and the finishing weight. That is how we prepared and tested the purity of the
organic solid we made.
The key methods that we used include the precipitation of crystallization and
recrystallization. Crystallization is the process where crystalline products are formed out of
other phases, whether it’s a solid, liquid, or vapor. The crystals that form are constituent
molecules, atoms, or ions. These are arranged in fixed and rigid repeating three-dimensional
pattern or lattice, crystals can be formed in different shapes and sizes. The ways that crystals
can form include cooling, antisolvent, evaporation, and reactive. The way we choose to form
crystals was through cooling. Crystallization is important because the product performance
is particularly crucial when it comes to making chemicals like aspirin as this needs the
chemical purity and the correct structure and it needs to be a strictly controlled substance.
This process is effective and efficient because many different steps help the product and
make the process more accurate. (1)
Recrystallization is the process to purify solids. During recrystallization, the impure solid
compound is dissolved in a hot liquid until the solution is saturated, and then the liquid is
allowed to cool. The solvent will either dissolve and leave a pure sample of the desired solid
in the minimum amount of solvent required. To ensure all solids are recrystallized when it
cools, therefore the slower the cooling the larger crystals are formed. When the solute and
the concentration of the solvent are equal these are called saturated solutions. If the
concentration of the solute is less than the solvent this makes it unsaturated although if
there is an excess of solute compared to the solvent, this is a supersaturated solution. A
supersaturated solution is a solution that contains more than the maximum amount of the
solute that is capable of being dissolved at a certain temperature, the amount will change
depending on the temperature the solute has been dissolved at. The recrystallization of the
excess solvent in the supersaturated solution is put in by adding tiny crystals of solute, these
are called seed crystals. These provide a nucleation site on which the excess dissolved
crystals can begin to grow. Therefore, meaning the recrystallization from a supersaturated
solution is very fast. This is also an example of a non-equilibrium state. The filtration we
used is known as gravity filtration this is using the conical filter paper. The solvent may form
a seal between the funnel and the filter paper, preventing displaced air from escaping and
considerably slowing down the filtration process. Although on the other hand the fluted
filter paper allows air to enter the flask, therefore equilizing the pressure which increases
the speed of filtration The fluted filter paper also provides a larger surface area through
which the solvent can seep. These two factors expedite the filtration process when the
fluted paper is used instead of the conical filter paper. Another form of filtration is hot
filtration. A hot filtration is used for filtering solutions that will crystallize when allowed to
cool. It is therefore important that the funnel is kept hot during filtration .The final form of
filtration is vacuum filtration which is the filtration we used. Vacuum filtration is a technique
for separating a solid product from a liquid. The mixture of solid and liquid is poured
through a filter paper in a Buchner funnel. The solid is trapped by the filter and the liquid is
drawn through the funnel into the flask below by a vacuum.
We used evaporation and a drying process to remove the solvents by the various methods
such as the evaporation from a crystallization dish or other suitable containers, another way
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