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Chemistry · 8. Organic chemistry and functional groups

Structure, functional groups and organic reactions

Recognise functional groups, predict products and connect conditions with equilibrium and safety.

40 minutesContent version: 2.1
Start the interactive pathwayOpen the virtual experiment

Driving question

How do functional groups control reaction type and properties?

Curriculum coverage

Vietnam Chemistry 11–12; IGCSE/AS organic chemistry.

Model scope and limitations

The school model uses representative reactions; odour is neither safe nor specific identification.

Learning objectives

  • Recognise alkane, alkene, alcohol, acid and ester groups.
  • Write esterification equations and state reversibility.
  • Predict conditions, observations and hazards.

Prerequisite knowledge

  • Structural formulae and covalent bonds.

Core knowledge

Functional group

A functional group controls characteristic reactions within a homologous series.

Esterification

Carboxylic acid + alcohol ⇌ ester + water with acid catalyst and heating.

Equilibrium

Using excess reactant or removing water/product can improve equilibrium yield.

Worked example

CH₃COOH + C₂H₅OH ⇌ CH₃COOC₂H₅ + H₂O. The ester name combines ethyl and ethanoate.

Misconceptions to avoid

  • Ethyl ethanoate is slightly soluble, not completely insoluble, in water.
  • Never smell directly; a “fruity smell” is not unique proof of an ester.

Virtual experiment procedure: Esterification

  1. Identify functional groups and predict the product first.
  2. Compare runs with/without catalyst and heating.
  3. Record layers, time and the limitations of odour observations.

Safety and cautions

  • Ethanol/esters are flammable and concentrated H₂SO₄ is corrosive; use a water bath, eye protection and no direct smelling.

Evidence to collect

  • Equation, product name, layer observation and equilibrium explanation.
Open the virtual experiment

Diagnostic check

1. The alcohol functional group is?

  1. –OH
  2. –COOH
  3. C=C only
Show answer and explanation

Correct answer: –OH

Alcohols contain a hydroxyl –OH on carbon.

2. Which small molecule also forms in esterification?

  1. H₂O
  2. O₂
  3. N₂
Show answer and explanation

Correct answer: H₂O

It is a condensation reaction producing water.

3. Safer heating source with ethanol?

  1. Water bath/electric heater
  2. Direct flame
  3. Flame in sealed vessel
Show answer and explanation

Correct answer: Water bath/electric heater

Avoid flames near flammable liquids.

Application practice

1. Ethanoic acid + methanol gives which ester?

  1. Methyl ethanoate
  2. Ethyl methanoate
  3. Methane
Show answer and explanation

Correct answer: Methyl ethanoate

Methanol gives methyl; the acid gives ethanoate.

2. Main role of H⁺ in esterification?

  1. Catalyst
  2. Final product
  3. Indicator
Show answer and explanation

Correct answer: Catalyst

H⁺ participates in the mechanism and is regenerated.

3. What can excess alcohol do?

  1. Shift equilibrium toward ester
  2. Stop all collisions
  3. Turn ester into ions
Show answer and explanation

Correct answer: Shift equilibrium toward ester

Le Châtelier predicts a shift that consumes added reactant.

Academic references

  1. OpenStax Chemistry 2e — peer-reviewed general chemistry
  2. IUPAC Gold Book — authoritative chemical terminology
  3. BIPM — SI Brochure, 9th edition

This lesson is maintained against the cited sources below. Simulations are learning models and do not replace supervised physical-laboratory safety procedures.

Content publisher
WebLab STEM
Technical maintainer
Đức Tiến — Control & Automation Engineer