how esters are formed

Investigative question: how are esters formed ? Esters are formed by the reaction of an alcohol and a carboxylic acid, usually in the presence of sulphuric acid to catalyse the process, or by the reaction of an acyl chloride with a carboxylic acid (this requires no catalyst and is irreversible without additional reactants) are the most common ways used. Others include reactions of certain molecules such as structural rearrangement.

Apparatus: Plastic dropping pipettes,
Beaker (100 cm3 or 250 cm3), (Note 1)
Test-tubes, 4
Test-tube rack
Bunsen burner
Heat resistant mat
Tripod and gauze
Crucible tongs

chemicals- Glacial (concentrated) ethanoic acid (CORROSIVE), about 2 cm3
Propanoic acid (CORROSIVE), about 2 cm3
Benzoic acid (HARMFUL), about 0.2 g
Concentrated sulfuric acid (CORROSIVE), 5-10 drops (Note 2)
Access to the following alcohols – about 10 drops of each required (Note 3):
Methanol (HIGHLY FLAMMABLE, TOXIC)
Ethanol (HIGHLY FLAMMABLE and HARMFUL if using Industrial Denatured Alcohol, IDA)
Propan-1-ol (HIGHLY FLAMMABLE, IRRITANT)
Butan-1-ol (HARMFUL)
One or more other alcohols, as available, from:
Butan-2-ol (IRRITANT)
Propan-2-ol (HIGHLY FLAMMABLE, IRRITANT)
2-Methylpropan-1-ol (IRRITANT)
Sodium carbonate solution, 0.5 M, about 10 cm3 per ester

Method- a Add 10 drops of ethanoic acid (or propanoic acid) to the sulfuric acid in the specimen tube. b Add 10 drops of ethanol (or other alcohol) to the mixture. c Put about 10 cm3 of water into the 100 cm3 beaker. Carefully lower the tube into the beaker so that it stands upright. d Heat the beaker gently on a tripod and gauze until the water begins to boil, then stop heating. e Stand for 1 minute in the hot water. If the mixture in the tube boils, use the tongs to lift it out of the water until boiling stops, then return it to the hot water. f After 1 minute, using tongs, carefully remove the tube and allow it to cool on the heat resistant mat. g When cool, pour the mixture