Skip to content
Dabour HubLEARN · PRACTICE · EXPLORESign inStudent

4.7Organic Chemistry

Esters — Edexcel Linear - OL (Chemistry) Revision Notes & Topical Questions

5 min read 8 parts Lesson 13 of 18 Unit quiz

📚 Edexcel Linear - OL (Chemistry) Hub / Topical Revision
🩺
100% Curriculum Specification Match Lesson Doctor Verified
The only platform with 100% curriculum specification match and verified interactive question banks.
Curriculum Equation Key Esterification Reaction EquationFast Exam Solution
R-COOH + R2-OH ⇌ (conc. H₂SO₄) R-COO-R2 + H₂O
0%read
Lesson summary

Esters: Formation, Naming and Uses — EDEXCEL LINEAR – OL (CHEMISTRY) notes: Name esters, describe how they are made from alcohols and carboxylic acids and give their properties and uses.Esters are organic compounds containing the ester link –COO– and are formed when a carboxylic …

  • Worked example 1
  • Worked example 2
  • Worked example 3
  • Worked example 4
  • Esterification
  • Hydrolysis

Part 1 of 5What are esters?

Esters are organic compounds containing the ester link –COO– and are formed when a carboxylic acid reacts with an alcohol.

What are esters?
They are volatile, colourless liquids with sweet, fruity smells, which are responsible for the flavour and fragrance of many fruits and flowers.
Esters are sparingly soluble in water, have lower boiling points than the acid or alcohol they come from (no hydrogen bonding between ester molecules),
  • and are flammable.

Part 2 of 5Esterification

An alcohol and a carboxylic acid are warmed with a few drops of concentrated sulfuric acid as catalyst. The reaction is reversible and also produces water:

ethanoic acid + ethanol ⇌ ethyl ethanoate + water

CH3COOH + C2H5OH ⇌ CH3COOC2H5 + H2O

1
Place equal volumes of the alcohol and acid in a boiling tube; add a few drops of concentrated sulfuric acid.
2
Heat gently in a water bath (not a naked flame as the reactants are flammable) for several minutes.
3
Pour the product into a beaker of sodium carbonate solution, which neutralises unreacted acid.
4
Smell cautiously by wafting; a sweet fruity smell shows the ester has formed, and the ester forms an oily layer on top of the water.

Part 3 of 5Naming esters

The name has two partsthe first word comes from the alcohol (-yl) and the second word comes from the acid (-oate).

Naming esters
Ethanol + ethanoic acid gives ethyl ethanoate; methanol + propanoic acid gives methyl propanoate; propanol + methanoic acid gives propyl methanoate.
To work backwards from a formula, find the C(=O)O link; the carbons attached to the carbonyl side (including the C=O carbon) come from the acid,
  • and those on the oxygen side come from the alcohol.
AlcoholAcidEster
MethanolEthanoic acidMethyl ethanoate
EthanolPropanoic acidEthyl propanoate
Propan-1-olEthanoic acidPropyl ethanoate

Part 4 of 5Uses and hydrolysis

Esters are used as food flavourings and perfumes, as solvents (nail varnish remover, ethyl ethanoate) and in making polyesters. Hydrolysis with acid or alkali splits an ester back into an alcohol and a carboxylic acid (or its salt); hydrolysis of fats with sodium hydroxide makes soap and glycerol.

Part 5 of 5Worked examples

  1. Name the ester formed from propanol and ethanoic acid and write the word equation. [3]3 marks

  2. Why is concentrated sulfuric acid added? [1]1 mark

  3. Why is the mixture heated in a water bath? [1]1 mark

  4. Give two uses of esters. [2]2 marks

Key terms

TermMeaning
EsterCompound with the –COO– link formed from acid and alcohol
EsterificationReaction of acid and alcohol to make an ester
HydrolysisSplitting by water, acid or alkali
CatalystConcentrated sulfuric acid in esterification
VolatileEasily evaporates
Ester linkThe –COO– group

Avoid these mistakes

1
Writing the acid part first in the name.
2
Forgetting that water is a product.
3
Heating with a naked flame.
4
Thinking the reaction goes to completion.

Last updated:

\n