Unit 4 - Laboratory Techniques and their Application
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Applied Science Unit 4 Assignment - Learning Aim B
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Unit 4 - Laboratory Techniques and their Application
Institution
PEARSON (PEARSON)
Production of an Ester - Nail Varnish Remover (Ethyl Ethanoate).
Whole Assignment: Includes the Experiment Theory, Techniques, Method, Risks, Results, Calculations.
Graded at DISTINCTION.
References also included.
Unit 4 - Laboratory Techniques and their Application
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Producing nail varnish remover
The objective of this experiment is to provide evidence that I understand how esters
are produced both in a laboratory and on an industrial scale.
The principle of reflux and distillation
Reflux keeps reactants at a constant temperature while preventing any vapours
from being lost to the atmosphere. For many reactions, controlled heating of the
reactants ensures optimal conditions for chemical processes, allowing the reaction
to occur faster. If carried out correctly, the reflux conditions should prevent any
vapours (unreacted compounds) from being lost to the atmosphere. While the
reactants are being kept at a high temperature, the area where vapours can be lost
should be kept at a low temperature so that the vapor will condense and fall back
into the solvent to react. This increases the purity, producing better yields.
Referring to laboratory reflux, the reactants are heated within a round-bottomed
flask and the opening is connected to a Liebig condenser which is a tube with two
layers, allowing water to flow through the outer layer. This water should be cold to
create a low atmosphere and condense any vapours back into the flask.
https://www.thesciencehive.co.uk/alcohols
On an industrial scale, a higher yield needs to be manufactured requiring larger
pieces of equipment. Although reflux individually is not widely used in the industry,
fractional distillation is a significant process to the industry, and it is a combination
of reflux with distillation. This occurs within large distillation columns.
So, reflux is a method that involves heating the reactants to the boiling point of the
reaction solvent and using a condenser to condense any reaction vapors back into
the solvent, providing the reactants with more energy and time to occur.
Distillation also involves evaporation and condensation; however, the intention of
distillation is to separate components of miscible mixtures (a mixture consisting of
liquids that are soluble in one another) to purify the component in demand, not to
ensure they have reacted. Referring to laboratory distillation, which is also known
as simple distillation because it only involves purifying one component (at a time),
the mixture is still heated within a round-bottomed flask, but it is heated to the
boiling point of the component which needs to be separated. A Liebig condenser is
still used but at a different position:
,https://www.alamy.com/stock-photo-distillation-120696859.html
The condenser is positioned at a downward angle between the round-bottomed
flask and an empty conical flask to produce a pure component also known as the
distillate.
On an industrial scale, fractional distillation is used to purify each component within
a mixture, producing many fractions of distillate. A natural mixture that distillates
many high demand products is crude oil:
https://www.pinterest.cl/pin/683280574701089047/
The Crude oil is heated to 400 degrees within a container connected to the fractionating column. At 400
degrees most of the crude oil contents will have reached its boiling point hence will be in the gas state
and diffuse into the fractionating column. The column consists of different sections and the higher the
section, the lower the temperature. The lowest section has a temperature of 350 degrees and the
, highest is 25 degrees. Crude oil is a mixture of different length hydrocarbons which condense at
different temperatures. So, as the hydrocarbons travel up the fractionating column and condense within
the different temperature sections, they are separated. The longest hydrocarbons within the
fractionating column will condense within the first sections because the longer the hydrocarbon chain
length, the higher the boiling point hence the higher the condensation point. Longer molecules have a
higher boiling point because of stronger intermolecular force, meaning more energy is required to
separate the molecules. Vice versa occurs with the short chain hydrocarbons: the shorter hydrocarbons
will condense within the latter sections because the shorter the hydrocarbon chain length, the lower the
boiling point hence the lower the condensation point.
Solvent extraction (also known as liquid-liquid extraction)
Solvent extraction is a process which extracts a compound from a liquid by utilizing
immiscible liquids. Immiscible liquids are liquids that are not soluble in one another
due to their differences of polarity. So, when added to each other they form an
immiscible mixture of layers, the denser liquid below the less dense liquid. Solvent
extraction typically uses an aqueous phase and organic phase as the immiscible
mixture. To perform the extraction, the solvents will require a separating funnel
which should have a funnel tap at the bottom of it.
https://
www.researchgate.net/figure/Diagrammatic-illustration-of-liquid-liquid-extraction-
adapted-from-Nichols-100_fig1_353282886
So, if a compound is dissolved in an aqueous phase and an organic phase is added
which the compound can dissolve more readily within, the compound will diffuse
into the organic compound. To make it more time efficient, shake the solvents when
added together. Once it has settled and separated, the denser layer at the bottom
of the funnel can be slowly drawn out into a beaker. The compound can then be
separated from the organic compound by evaporating the organic compound.
Testing methods and their principles:
The products need to be tested to ensure they are pure enough.
Spectroscopy uses the principle that different substances either absorb, emit,
or scatter electromagnetic radiation. The electromagnetic spectrum displays
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