Unit 4 - Laboratory Techniques and their Application
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Applied Science: Unit 4 - Assignment 3 (Preparation of Ethyl Ethanoate)
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Unit 4 - Laboratory Techniques and their Application
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PEARSON (PEARSON)
This assignment is a compulsory assignment in applied science, which covers the laboratory techniques used within the medical industry (i.e. pharmaceutical and medical researching organisations) and their applications within both the workplace and the laboratory within both colleges and universitie...
unit 4 laboratory techniques and their applications
level 3 biomedical science
synthesising ethyl ethanoate
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BTEC
PEARSON (PEARSON)
Applied Science 2016 NQF
Unit 4 - Laboratory Techniques and their Application
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Assignment 2 – Unit 4
Laboratory Techniques and their Application
Making Nail Varnish Remover (Preparation of Ethyl Ethanoate)
An Introduction to the Report
Many liquid (and solid) products manufactured within the production industry for selling in retail shops and
industries would often utilise a specialised chemical which provides volatility, giving the product beneficial
properties such as fragrances which may well affect the consumers decision on purchase. This often effective
marketing technique is primarily achieved through the implementation of a chemical ester; an added substance
derived from the reaction between a carboxylic acid and an alcohol (for example ethanol).
A carboxylic acid is any organic acid within the carboxyl functional group. This group is made from the bonding
between two other functional groups; a hydroxyl group (OH), and another carbonyl (C double-bonded O [C=O]).
These two groups bonded together will form the carboxylic acid, with an example of this phenomenon being
shown in ethanoic acid (also known as acectic acid [Latin for “acetum” or ‘sour wine’]), where the substance will
react with the surrounding gaseous oxygen molecules present within the air, forming the chemical formula,
CH3C=O-OH. Ethanol, with an initial chemical formula of H3C-CH2-OH, would react with the present oxygen [O2]
molecules by losing its two hydrogen [H] atoms bonded to the centre carbon molecule. This would result in the
by-product of water forming as a result as two hydrogen atoms bonded to a single oxygen atom forms the water
chemical formula; H2O. The additional oxygen molecule will be paired with the central carbon atom in a double
bond, where two electrons from each atom are shared between a covalent bond. Therefore, the chemical
equation for the example of ethanol includes:
Ethanol (l) Oxygen (g) Ethanoic Acid (l) Water (aq)
+ O H
H
[H3C2H2OH] [O2] [CH3COOH] [H2O]
In this example, ethanol is the alcohol with a hydroxide group [OH] already present within the chemical structure.
The carbonyl group is formed as the alcohol is oxidised, bonding the two hydrogen molecules to one of the two
oxygen atoms from the surrounding environment, allowing the remaining molecule to directly form a double bond
with the lone paired carbon, thus creating the carbonyl group. The ethanoic acid is the end result of the acid
formation, with water being the by-product.
After the formation of a carboxylic acid, in this case acectic acid, and its separation from the excess water, it can
now be utilised to form the ester. As previously stated, a carboxylic acid and an alcohol are required to form
these organic substances. This means that ethanol can be implemented once again to be used as the alcohol
against the acectic acid (in depth method and formation of the ester on page 3), forming the ester; ethyl
ethanoate (commonly named ‘ethyl acetate’). Ethanol is applied once again onto the carboxylic acid to form the
by-product of water due to the alcohol’s possession of a hydroxyl functional group. This OH polar bond will form
, 2
another covalent bond with the final hydrogen molecule located at the end of the oxygen atom within the
ethanoic acid, forming the aqueous H2O water substance that will require filtering after the esters initial formation.
This report will involve an in-depth formation and thorough analysis of an ethyl ethanoate sample constructed
within the laboratory. The primary aim of this investigation is to design an effective ester that contains as little
impurities as possible to prove the reliability and validity of the substance. Analysis of the ester after its formation
will be conducted using an infrared spectroscopy to allow for the ethyl ethanoate to absorb the infrared light,
which identifies each functional group via the stretches that spike on the graph, as well as picking up any
impurities contained within the mixture.
Analysis of Ethyl Ethanoate
Ethyl ethanoate is a common example of esters and is widely harnessed in the manufacturing of beauty products
such as perfumes and nail varnish removers. In 2004, an estimated 1.3 million tonnes was produced within the
same year worldwide as it’s overly effective and favourable properties to produce pleasant smells of fruit and its
ability to sustain little pressure before changing its ordinary state from a liquid to a gaseous form (volatility)
makes it effective in the production of perfumes as it quickly vaporises when exposed to the surrounding air.
Ethyl ethanoate has a melting point of -83oC and a boiling point of 77.06oC, meaning it possesses a lower melting
point and boiling point when compared to most other common substances such as water, which changes from a
solid to a liquid state at 0oC (32o Fahrenheit).
In appearance, ethyl ethanoate is a clear, colourless liquid that closely resembles the look of water. Though
water is also produced as a by-product of the formation of ethyl ethanoate, esters are mostly insoluble in water,
meaning they do not mix (this phenomenon is frequently seen in oil and water). This means that during the
practical in the production of ethyl ethanoate, filtration would be recommended to separate both solvents from
one another, though human error may affect the extraction process, e.g. small volumes of water may be filtered
with the ester.
The process of producing any ester solvent is formally known as esterification; where (as previously mentioned)
an alcohol is heated against a carboxylic acid to form the ester compound and the excess water. The formation
of excess water also means that esterification results in a condensation reaction as the hydroxyl group within the
ethanol would form a polar covalent bond with the remaining hydrogen molecule within the ethanoic acid.
Risk Assessment
When undertaking esterification and purification, there are many risk factors that may well impact the well-being
of the person taking part in the practical, or others who are nearby. To minimise the risks of potential hazards
that can inflict damage upon ones physical health, a risk assessment is required to understand both the types of
risks that may arise and the appropriate control measures utilised to ensure that hazards are less severe, and
that the potential damage is minimal.
[RISK ASSESSMENT SEPARATE]
, 3
Producing the Ethyl Ethanoate Ester (Student’s Practical)
To begin, the student ensured that all necessary equipment was calibrated before the practical was continued as
any instrumental errors caused from electrical measuring equipment would provide inaccurate readings, which
would’ve led to unreliable and ineffective results. By undertaking calibration of the electrical equipment such as
the scales, this reduced the chances of systematic error that would poorly affect the student’s final results.
After calibration, the student first applied 15cm3 of ethanol (alcohol) along with an additional 10cm3 of glacial
ethanoic acid (carboxylic acid) into a 50cm3 round-bottomed flask to be used as the container during the heating
process in the formation of the ester. The student utilised a round-bottomed flask over a beaker as the curved
surface area allowed the mixture to be heated evenly, which made sure that both solvents were blended. If either
the acid or the alcohol was not efficiently heated in the production of the ester, then this would affect the final
mass of the ethyl ethanoate, which was especially needed for future use within the calculation of the yield. As the
ethanol and the ethanoic acid was applied into the flask, a 5cm3 teat pipette was used by the student to prevent
the risk of spillage from pouring. It was important to monitor the activity of the chemicals used and how they were
extracted and imported into flasks as corrosive material in particular, can damage any exposed skin or stain
surfaces. A pipette also ensured additional accuracy in the amount of alcohol to acid volume as it was important
for the student to not dilute either of the substances otherwise it may take longer for the catalyst to speed up the
rate of reaction, as well as wasting material.
Shortly after the alcohol and acid were applied, the student implemented a small spatula of anti-bumping
granules that reduced the intensity of the reaction when it was placed under heat as the initial heat energy
provided to the reaction allowed for the vigorous movement of molecules. Though through the appliance of anti-
bumping granules, this causes an even boiling as a result; this reduces splashing of the chemicals during
esterification, which maintains the amount of ester that remains within the flask as none would be lost as a result
to vigorous splashing or spillage.
The formation of an ester can be an incredibly slow process at room temperature with the presence of time being
a crucial and important yet costly resource that the student didn’t wish to wait out. Fortunately, the process of
esterification had the ability to be sped up when accompanied with a chemical catalyst. A catalyst is defined as
any chemical/solid that possesses the ability to speed up the rate of reactions. During this experiment, the
student made use of exactly 1cm3 of concentrated sulfuric acid solution, where they ensured that it was applied
slowly as the appliance of too much catalyst within a short space of time would have resulted in a vigorous
reaction of bubbling as a result. After the sulfuric acid was applied to the mixture, the student gently swirled the
round-bottomed flask to allow for the catalyst to mix with the acid and alcohol. It was important for the student to
not rapidly shake the flask as this may well have formed air bubbles or the added pressure would force any
vapour to escape from the ester as the rapid shaking of liquids would prove to increase temperature. As
previously stated, esters consist of a low melting point and are volatile; meaning any added pressure and/or heat
may cause a minor loss in volume from the final product of ethyl ethanoate. If this were to happen, then this
would affect the overall yield of the ester, which would have made the final results unreliable and inaccurate.
After the ethanol, ethanoic acid, anti-bumping granules and the catalyst were applied to the round-bottomed
flask, any vapour that would escape during the heating process of the ester would have meant that the final mass
of the ester would be much lower than the theoretical mass, which was one of the main priorities that the actual
mass needed to meet (or be near enough to). To prevent the escape of the valuable ester vapour, a reflux
reaction was undertaken by the student to consistently condense the gas back into liquid form as small volumes
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