Unit 4 - Laboratory Techniques and their Application
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Unit 4 Learning Aim B (making ethyl ethanoate)
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Unit 4 - Laboratory Techniques and their Application
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PEARSON (PEARSON)
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Unit 4 - Laboratory Techniques and their Application
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Mohammed Salam Unit 2 LA: B
Making a nail varnish remover
Conclusions from the practical:
The purity of the sample was checked by distilling the sample and collect the distillate at the boiling
point of the ethyl ethanoate, the purity of the sample was 52.43%.
Ethyl ethanoate was formed when ethanoic acid started to react with ethanol, and it also formed
water. After ethyl ethanoate was formed, it was left to dry in the boiling tube where it weighed
82.670 grams but before putting the ethyl ethanoate into the boiling tube it was weighed as 29.731
grams. To calculate how much it was formed firstly, take the mass of boiling tube with ethyl
ethanoate away from the mass of boiling tube, which is then calculated as 52.939 grams, so 52.939
grams of ethyl ethanoate was formed.
The purity of ethyl ethanoate was shown by the percentage yield of the ethyl ethanoate which was
52.43% which states that the sample was not pure. Only 52.43% of ethyl ethanoate was pure which
also suggested that 47.57% was impure. The impurity of the sample occurred due to the boiling
temperature of ethyl ethanoate which meant that the starting materials did not dissolve properly
and therefore altered the percentage yield.
The boiling point for the sample was 74 °C whereas the literature value for boiling point was 77.1 °C
which means that my sample was below the literature value. This could be due to the amount of
impurities that could occur in the sample where it can affect the temperature boiling point range of
ethyl ethanoate. Another sources of error could occur due to the limited time that I had during the
practical, the solution for resolving the issue is that doing more of repeated tests of ethyl ethanoate
could improve the boiling point range.
(Conclusion) Science techniques used:
Conclusions with the scientific techniques used in the practical:
Reflux is a technique that was used in the practical, equipped it with a condenser so that it was set
up for heating mantle with reflux. Clamped the condenser. The condenser featured two holes where
one of them is fitted with a hose to allow the water to escape and the other hole was fitted with a
hose, but it was also connected with a running cold tap water, this is to allow the water to enter the
condenser apparatus. During the experiment, the condenser allows to cool the solution of ethyl
ethanoate simultaneously this is to ensure so that there will be equilibrium temperature. When the
solution was heated up by a heating mantle the solution turned into a vapour and reached the
condenser when it did reach the condenser it formed back into liquid, this is due to the heat loss
from the vapour.
Distillation was also a technique that was used in the practical where the sample was distilled until
no more distillates comes over, the remaining liquid was left in the round bottomed flask, and it was
also not distilled to dryness. This is because an empty glassware will cause the temperature to
increase quickly and may break the glassware. So, leaving some liquid in the round bottomed flask
will prevent the overheat and it will also prevent it from breaking. The distillation allows to almost
purify the sample in the practical.
Separation to isolate the ethyl ethanoate is one of the most important techniques that was used in
the practical. This can be done easily as ethyl ethanoate is less dense than water, so the formation of
ethyl ethanoate was formed above the solution. The mixture was first transferred to a separating
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, Mohammed Salam Unit 2 LA: B
funnel and added about 25 cm3 of 30 percent of sodium carbonate solution. The sodium carbonate
solution allows to separate the ethyl ethanoate from the solution. Used a stopper and then turned it
upside down gently and then opened the stopcock to vent the system. it was inverted to at least 15-
16 times. Removed the stopper, opened the stopcock, and slowly drained off the waste aqueous
layer that was formed from the solution where the wasted aqueous layer was transferred into a
50cm3 waste beaker, then closed the stopcock. The remaining of ethyl ethanoate was transferred to
a dry boiling tube where it was contained with anhydrous calcium chloride. Anhydrous calcium
chloride absorbs the water from the solution. Decanted the ethyl ethanoate into a clean and dry
50cm3 pear shaped flask.
Tested the purity of the sample (ethyl ethanoate) by determining the boiling point, so heating device
was used to heat up the sample. Heated up the sample until it started to boil, watched, and
recorded the full range at which it boils. This was also compared with the literature value to identify
whether it is pure or impure.
Reflux – condenser was used to set up the reflux, the condenser was also fitted with running cold tap
water so that there would be equilibrium of temperature. I operated the heating mantle and
adjusted the temperature to higher until the mixture in the flask was boiling. It was left to boil for 15
minutes and after that I allowed the mixture to cool down.
Distillation – anti bumping granules was used in the distillation process. I distilled the ethyl
ethanoate until there was no more distillate left.
Separation to isolate ethyl ethanoate – heating up ethyl ethanoate to get rid of the excess of any
starting materials and it was cleaned it with distilled water and dried the ethyl ethanoate.
Industrial production of ethyl ethanoate:
Ethyl ethanoate is a solvent that is used in pharmaceuticals and food industry due to its fruity taste
when it is diluted so the ethyl ethanoate is used as a flavour enhancer.
The starting materials are ethanol + ethanoic acid with a sulphuric acid as a catalyst.
In general, Fischer Esterification occurs through nucleophilic addition-elimination, replacing the OH
group by the OR. Typically, this happens when sulfuric acid are used as a refluxing acid. As these
acids dissolve in alcohol, they form the alcohol's conjugate acid, which acts as the catalyst for
reaction. According to Le Chatelier's principle, all steps of the Fischer esterification are reversible
and alcohol in excess can be added to the reaction mixture to prevent equilibrium from shifting in
flavour of the ester product. Removing water from the reaction mixture is another strategy that can
push the equilibrium in the right direction.
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