Unit 4 - P2, P3, M2, D2 - Separating and Estimating Purity
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Course
Unit 4 - Scientific Practical Techniques
Institution
PEARSON (PEARSON)
This is my full assignment for my distinction graded unit 4.
It includes; fluency, structure, photographs, diagrams, full reference list, little to no plagiarism plus more that are not included in the singular tasks!
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Precipitation:
This photograph is showing the end result of barium
chloride mixed with unknown compounds.
Chemical precipitation is the forming of a solid from a
solution. In the test tubes unknown compounds are placed
as well pipetting in barium chloride and hydrochloric acid.
Sulfate ions bind with the unknown compounds and
creating a sulfate precipitate
Crystallisation:
This photograph is showing the cooling of acetylsalicylic acid to form
crystals.
Crystallisation is a physical change where a solid that has been
dissolved is separated from a liquid. The acetylsalicylic acid is cooled
until crystals start to form. Once this is done the flask is place into an
ice bath as this allows the maximum of crystals to form. While
cooling, the acetylsalicylic acid was being constantly stirred with a
glass rod to also maximise the formation of crystals.
Filtration:
These photographs are showing the
acetylsalicylic acid being removed of any liquids
present.
Filtration is a process that allows a liquid to be
separated from a solid by allowing the liquid to
pass through but not the solid. The acetylsalicylic
acid crystals are poured onto the filter paper that
has been soaked in water and filtered. This allows
for the liquid in the acetylsalicylic acid to be
filtered out easier. The vacuum pump is then
turned on and left on until the acetylsalicylic acid
has been removed of all liquid.
Drying:
This photograph is showing the acetylsalicylic acid after being dried.
Drying is a process of removing water from a substance. Because the
experiment was unable to be carried out in one go, our acetylsalicylic acid
samples were put into flasks where they were left to dry for a couple of
days before coming back to them.
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, Distillation:
This photograph is showing the process of distillation.
Distillation is a process that purifies a liquid with heating and cooling. Alcohol and water have two
different boiling points and so the alcohol evaporated before the water. The evaporated alcohol
cools and goes down the condensation tube into a flask. This causes the separation of alcohol and
water.
Solvent extraction:
This photograph is showing the dried acetylsalicylic acid dissolved in
water and ethanol.
Solvent extraction is the process of separating compounds based on
their relative solubilities. To the dried acetylsalicylic acid, ethanol and
warm water are added and mixed in a warm water bath until all solids
are dissolved. This allows for impurities being insoluble in the ethanol to
be filtered out leaving a pure sample behind.
Recrystallisation:
This photograph is showing crystals reforming after the product has
been purified using ethanol and water.
Recrystallisation is the process of purifying compounds. The
acetylsalicylic acid that has been dissolved in a solvent is then placed
into an ice bath which allows crystals to reform again. Once the crystals
are formed a solution is left behind and this solution should contain all
the impurities in the acetylsalicylic acid. So, when the sample is put
through the vacuum pump again, all impurities are filtered out leaving
behind a pure sample of aspirin.
Chromatography:
This photograph is showing both pure and self-made aspirin samples on the
chromatography paper. The paper is absorbing the alcohol and is starting to
work its way up.
Chromatography is the process of separating a mixture into the different
components. Our sample and a pure shop bought aspirin sample were
mixed with ethanol as it evaporates once on the paper leaving just the
aspirin samples on the chromatography paper. The mixture was dotted on
with capillary tubes and then placed upright in a beaker of ethanol with a
mat over the top to stop the evaporation of ethanol. This was left for the
solvent to make its way up the paper.
Electrophoresis:
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