BTEC Science Unit 4: Laboratory Techniques and their Application is a course designed for students who are interested in pursuing a career in science. This unit focuses on developing the knowledge and skills required to conduct laboratory experiments and analyze data using various laboratory techni...
Unit 4 Assignment B:
Be able to use scientific techniques to
separate and assess purity of substances
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Separation and Estimating Purity
What are esters and what are they used for?
Esters are compounds that are widely used by industries as solvents and as a reactant for
making polyesters. Esters have sweet scents, and are very common in nature [1]. Around
Europe the smell of bananas is made using the ester called 3-methylbutyl acetate [2].
What is ethyl ethanoate?
Ethyl ethanoate is a type of ester that can be used to make items such as glue and nail
polish remover. It is also used to remove caffeine from tea and coffee [2].
Equation for ethyl ethanoate:
Ethanoic acid + ethanol ethyl ethanoate + water
CH3COOH + C2H5OH CH3COOC2H5 + H2O
[2]
,INTRODUCTION:
Ethyl ethanoate is a product of ethanoic acid (a carboxylic acid) and ethanol (alcohol). To make the actual ethyl
ethanoate I had to use a procedure known as reflux. Reflux is a technique which involves boiling the mixture of
ethanoic acid, ethanol, sulfuric acid (a catalyst) on a heating mantle until the reactants fully react - this can be
determined when a strong vinegar-like scent is produced.
EQUIPMENT:
● 2 10cm3 measuring cylinders
● 1 non-graduated pipette
● Anti-bumping granules
● 1 spatula
● 1 stopwatch
● 1 liebig condenser with the water in and out tubes
● 1 25cm3 round-bottomed conical flask with a lid
● 10cm3 glacial ethanoic acid
● 15cm3 ethanol
● 1cm3 of concentrated sulphuric acid
● 1 heating mantle
● 1 clamp
● 1 clamp stand
METHOD
Measure out 15cm3 of ethanol with a measuring cylinder and pour it into the 25cm3 round-bottomed conical
flask, then measure out 10cm3 of glacial ethanoic acid with a separate measuring cylinder and pour it into the
conical flask containing the ethanol. Then, add 1 cm3 of concentrated sulfuric acid to the conical flask using a
spatula of anti-bumping grains. Swirl the flask around until most of it is combined.
Then, prepare for reflux by obtaining the liebig condenser, connecting the top water in tube to the tap, and
placing the bottom water out tube in the sink so that water may depart. Attach the conical flask flask to the liebig
condenser, then use a clamp to secure the flask in place with the clamp stand, then lower the conical flask down
the clamp stand so it sits on the heating mantle, close the liebig condenser with the glass stopper, and heat the
mixture in this setup until the reactants have reacted to produce ethyl ethanoate.
Risk assessment:
Hazard Risks How it can be reduced
Glass equipment If glass equipment is placed near Glass should be stored away from
the edge of a table it can break to the centre of the table, and any
shards and cut skin. damaged equipment should be
discarded right away.
Ethanol Is highly flammable There should be no open flames
near the ethanol. [4]
Glacial ethanoic acid Is flammable and corrosive All sources of fire should be kept
away from the ethanoic acid and
gloves should be worn while it is
being handled.
[5]
Concentrated sulphuric acid Is corrosives Disposable gloves should be worn
and the sulfuric acid should not be
touched directly. [6]
Heating mantle Can reach very high temperatures The heating mantle should be
- heat up equipment as well and turned off while the apparatus is
cause mild to moderate burns being set up and once the ethyl
, ethanoate is getting heated the
round-bottomed conical flask as
well as any other bit of the
apparatus should not be touched.
Simple distillation of ethyl ethanoate - part 2:
INTRODUCTION
Simple distillation is used to get a distillate from a solution. This process involves the ethyl ethanoate collected
from part 1 evaporating out of the condenser into a clean dry beaker.
Equipments needed
● 1 25cm3 round-bottomed conical flask
● 1 liebig condenser
● 1 stopwatch
● The purified ethyl ethanoate collected from part 1 of the experiment in a round bottomed conical flask
● 1 clamp and 1 clamp stand
● 1 heating mantle
● 1 adapter and 1 claisen adapter
● 1 clean dry 100 ml beaker
METHOD FOR SIMPLE DISTILLATION OF ETHYL ETHANOATE:
1. Attach the liebig condenser to a clamp stand, then attach the claisen adaptor to the conical flask holding ethyl
ethanoate (put this ethyl ethanoate over a heating mantle), then connect 1 adaptor to one side of the liebig
condenser, this side will be above the clean dry beaker.
2. Once everything is in place, let a third of the ethyl ethanoate to evaporate and condense into the empty
beaker.
3. After collecting the third of the ethyl ethanoate, allow the device to cool to ambient temperature before
removing the beaker holding the ethyl ethanoate from the setup. The beaker's ethyl ethanoate should be
colourless.
Purification of the ethyl ethanoate - part 3:
INTRODUCTION
This part of the purification of the experiment involves using a separating funnel, distilled water and sodium
carbonate to wash the ester. The purpose of this purification of ethyl ethanoate is to make sure that there are no
impurities present in it.
METHOD FOR CLEANSING/WASHING OF ETHYL ETHANOATE:
1. First, pour the ethyl ethanoate into a separating funnel(that is clean and dry), then add 15cm3 of distilled water
to the separating funnel. Shake the funnel in an upwards and downwards motion, to allow the liquids to mix, then
hold it upright and wait for two distinct layers to form.
2. Once the two distinct layers form, let out some air from the top, close the top again with the lid, and remove the
bottom layer, which is the aqueous layer, the aqueous layer can be let out by opening the tap and letting out
small quantities of liquid until the aqueous layer surface leaves the funnel.
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