Lab 2
Date: 2nd October, 2023
Skill Assessed: M/M (pay close attention to volumes of reagents taken, measurements of
volumes, following the method, successfully obtaining an ester layer, safe handling of glassware
and corrosive chemicals and station clean-up)
Title: Esterification
Aim: To make ethyl ethanoate and isopropyl ethanoate
Apparatus: Glacial (concentrated) ethanoic acid (CORROSIVE) (15 ml), ethanol (10 ml),
isopropyl alcohol (10ml), concentrated sulfuric acid (CORROSIVE),0.5M sodium carbonate
solution (40 ml), boiling tubes (2), test tube rack (1), test tube holders (2), 50 ml beakers (4),
100ml beakers (1), water bath, 10ml measuring cylinder (2), droppers (2), distilled water
Method: Ten drops of concentrated sulphuric acid were placed into a clean, dry boiling tube. Six
ml of glacial ethanoic acid were added to the boiling tube. Four ml of ethanol were added to the
mixture. The contents of the boiling tube were shaken to ensure thorough mixing. The water in
the water bath was heated until the water began to boil, then heating was stopped. The boiling
tube was left for 20 minutes in the hot water. If the mixture in the tube boiled, it was quickly
removed from the water until boiling stopped and then returned to the hot water. The contents of
the tube were gently shaken periodically to ensure proper mixing. After 20 minutes, the boiling
tube was carefully removed and placed in a 100 ml beaker half filled with tap water and allowed
to completely cool. When cooling was complete, 20 ml of the 0.5 M sodium carbonate solution
were slowly added to the boiling tube in 5 ml portions. Effervescence occurred. The boiling tube
was shaken well to ensure thorough mixing. A layer of ester separated and floated on top of the
aqueous layer. If there was no separation, a 100 ml beaker was half filled with distilled water and
the mixture was added to it. The product was smelled by gently wafting the odor towards the
nose with the hand. Steps 1–9 were repeated using isopropyl alcohol instead of ethanol.
Results:
TABLE SHOWING THE ESTERS FORMED IN REACTION, THE NUMBER OF LAYERS
FORMED AND SMELLS OBSERVED
Ester Layers Scent
Methyl Ethanoate Two Favours acetone
Ethyl Ethanoate Two Favours Acetone
Isopropyl Ethanoate Two Fruity
Discussion: Esterification is a reversible reaction between a carboxylic acid and an alcohol in the
presence of a strong acid catalyst to produce an ester and water. In this experiment, glacial
ethanoic acid reacted with ethanol and isopropyl alcohol (propan-2-ol) to produce ethyl
ethanoate and isopropyl ethanoate respectively. The balanced chemical equations are as follows:
CH₃COOH + CH₃CH₂OH ⇌ CH₃COOCH₂CH₃ + H₂O
(Ethanoic acid + ethanol → ethyl ethanoate + water)
CH₃COOH + CH₃CH(OH)CH₃ ⇌ CH₃COOCH(CH₃)₂ + H₂O
(Ethanoic acid + isopropyl alcohol → isopropyl ethanoate + water)
In each case, two distinct layers were observed after the addition of sodium carbonate solution.
The upper layer was the ester due to its lower density and immiscibility in water. The scent of
ethyl ethanoate resembled acetone, which is consistent with its characteristic sweet, solvent-like
odor. Isopropyl ethanoate produced a stronger fruity smell, typical of esters used in artificial
flavors and fragrances.
The separation of the ester layer was easier for isopropyl ethanoate due to its relatively lower
solubility in water compared to ethyl ethanoate. The volume of ethanoic acid used was greater
than the alcohol to drive the equilibrium reaction towards ester formation, improving yield by
having the acid in excess.
The reaction mixture was not allowed to boil to prevent loss of volatile reactants and products.
Gentle heating ensures the reaction proceeds without decomposition or evaporation of the ester
formed. Concentrated sulfuric acid acted as a catalyst and dehydrating agent, shifting the
equilibrium by removing water. Sodium carbonate solution was added to neutralize excess acid
and help separate the ester layer, indicated by the effervescence due to carbon dioxide release.
Source of Error: Leaving the mixture in the tube to boil.
Conclusion: Ethyl ethanoate and isopropyl ethanoate were successfully prepared through
esterification. Both formed distinct ester layers and produced characteristic smells, confirming
their formation. Isopropyl ethanoate gave a more pronounced fruity scent and clearer separation,
likely due to its lower solubility in water.
