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Unit 2, learning aim C
- Institution
- PEARSON (PEARSON)
Distinction level assignment, for unit 2 learning aim C, for applied science
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Sarah Hill – 175220 Unit 4Unit 4: laboratory techniques and their applications. Learning aim C:
explore manufacturing techniques and testing methods for a 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, then I will be describing the industrial manufacture and
testing of an organic solid, then I will be demonstrating skilful application of techniques in
preparing and testing the purity of an organic solid and have will draw up conclusions, then I
will be comparing the laboratory and industrial manufacture and testing of an organic solid
and 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 these are part 1 which is the preparation and
then part 2 which 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 this into the conical flask and swirl the contents 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 the sulfuric acid is
used as a catalyse 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 pours its contents into water in a beaker and stir thoroughly to precipitate
the solid, then filter of the aspirin under reduced pressure but avoiding skin contact. 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 get the crystals and also the
unreacted solution is filtered off. Part 2 is the purification steps this is done by putting the
ethanol into a boiling tube. Then prepare a breaker with 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 then 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 the
crystals. Pour the hot solution into some water into a conical flask. If a solid separate 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 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 other the pure aspirin is left
on the filter paper; this is so when it is 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.
, Sarah Hill – 175220 Unit 4
The key methods that we used includes the precipitation of crystallisation and
recrystallisation. Crystallization is the process where crystalline products are formed out of
other phases, whether it’s a solid, liquid or vapour. The crystals that form are constituent
molecules, atoms or ions are arranged in some 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 the
form crystals was through cooling. Crystallization important because the product
performance is particular crucial when it comes to make chemical like aspirin as this needs
the chemical purity and the correct structure and it needs to be a strictly controlled
substance. As the process performance, is effective and efficient, this is because they are
many different steps that help the product and the process efficient and accurate. (1)
Recrystallisation is the process to purify solids, during recrystallisation and 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 the desired solid or the impurities to
leave a pure sample of the desired solid the minimum amount of solvent require and to
ensure all solids is recrystallisation when it cools therefore the slower the cooling the larger
crystals that form. When the solute and the solvents concentration 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 a 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 been dissolved at a certain temperature,
the amount will change depending on the temperature the solute is been dissolved at. The
recrystallisation of the excess solvent in the supersaturated solution 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 recrystallisation
from a supersaturated solution is very fast. This is also an example of a nonequilibrium
state. The filtration we used is known as gravity filtration this is with the use of the conical
filter paper, the solvent may form a seal between the funnel a the filter paper, preventing
displaced air from escaping and considerable slowing down the filtration process. Although
the fluted filter paper on the other hand allows air to enter the flask along its side to
equalize pressure, thereby increasing 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 crystallise when allowing cool. It is therefore important that the funnel is kept hot
during filtration through contact may prematurely form on the filter paper or in the stem or
the funnel. The final form of filtration is vacuum filtration which is the filtration we sued.
The vacuum filtration is a technique for separating a solid product for 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 drying process was the removal of solvents by the various
methods such as the evaporation from a crystallisation dish or other suitable containers,
another way is the oven drying the solvent, also the use of desiccator, another reason is the
use of chemical drying agents to remove water from a solution in an organic solvent, then
distillation and finally rotary evaporation and the effect of reduced pressure. The
Desiccators and the chemical drying agents, the chemicals that absorb solvent are placed in
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