Hydrocarbon Derivatives - Halocarbons and Esters

Grade 12 · Chemistry

Semester 1 | Period 2 | Week 9

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Subject: Chemistry

Semester: 1

Period: 2

Week: 9

School Name:
Teacher’s Name:
Subject: Chemistry
Grade Level: Grade 12
Week & Period: Week 9, Period II
Date:

Topic: Hydrocarbon Derivatives – Halocarbons and Esters

Subtopics:

  • Halocarbons (Alkyl Halides): classification, nomenclature, structure, properties, laboratory tests, and uses.
  • Alkyl Alkenoates (Esters): formation, structure, properties, reactions, and uses.

 

Learning Objectives:
By the end of this lesson, learners should be able to:

  1. Identify the structural features of halocarbons and esters.
  2. Name halocarbons and esters using IUPAC conventions.
  3. Describe and compare their physical and chemical properties.
  4. Conduct simple tests for halogenated compounds.
  5. Explain esterification and hydrolysis reactions.
  6. Outline industrial and biological uses of halocarbons and esters.

 

Previous Knowledge:
Learners have studied alcohols, acids, aldehydes, and ketones.

 

Instructional Materials:

  • Molecular models
  • Lab reagents (silver nitrate in ethanol, alcohol, and carboxylic acid)
  • Ester samples (banana essence, ethyl acetate)
  • Halocarbon samples (chloroform, CFCs, etc.)

 

Anticipation (Warm-Up) – 5 minutes:
Ask learners: “What do you get when an acid reacts with an alcohol?” Use responses to introduce esters.

 

Building Knowledge (Main Lesson) – 25 minutes:

  1. Halocarbons (Alkyl Halides):
    • Functional group: R–X (X = F, Cl, Br, I).
    • Classification: primary, secondary, tertiary halides.
    • Reactions: nucleophilic substitution (SN1/SN2), elimination.
    • Lab test: silver nitrate test to confirm halide presence.
    • Uses: solvents, refrigerants, anesthetics (CFCs), pesticides.
  2. Esters (Alkyl Alkenoates):
    • General formula: R–COOR’.
    • Formation by esterification of carboxylic acids and alcohols.
    • Hydrolysis in acidic or basic medium (saponification).
    • Pleasant smell – used in perfumes, food flavorings, solvents.
    • Examples: ethyl ethanoate, methyl salicylate.

 

Learners’ Activities:

  • Build molecular models of halocarbons and esters.
  • Perform silver nitrate test on a halide.
  • Synthesize an ester (teacher-led demonstration if equipment is limited).
  • Identify real-life uses of esters (e.g., smell of banana).

 

Consolidation (Review and Assessment) – 10 minutes:

  • Quiz: Identify and name given halocarbon and ester structures.
  • Draw esterification reaction of ethanol and ethanoic acid.
  • Explain how to distinguish between alkyl halide and ester in the lab.

 

Homework / Assignment:

  • Write out and balance the reaction for base hydrolysis of ethyl ethanoate.
  • Research one halocarbon and one ester used in the pharmaceutical industry.

 

Notes – Detailed and Explained:

  • Halocarbons are compounds where one or more hydrogen atoms in a hydrocarbon are replaced with halogen atoms (Cl, Br, I, or F). Their reactivity depends on the nature of the halogen and the carbon it is attached to. They are used in many industries but are also linked to ozone depletion (e.g., CFCs).
  • Esters are produced when carboxylic acids react with alcohols in a process called esterification, typically catalyzed by acid. They have fruity smells and are used in artificial flavoring. Esters undergo hydrolysis in the presence of water and acid/base to form acids and alcohols.

 

Expanded Notes / Instructions:

  • Explain environmental concerns of halocarbons and CFCs (ozone layer).
  • Discuss importance of esters in fragrances and everyday items.
  • Guide learners in balancing esterification and hydrolysis reactions.

 

Inclusive / Differentiation:

  • Visual aids and flashcards for functional groups.
  • Practical synthesis (demonstration or group experiment).
  • Use real-life analogies (e.g., perfume and banana essence).

 

Teacher’s Reflection (Post-Lesson Questions):

  • Were learners able to distinguish esters and halocarbons?
  • Did students grasp reaction mechanisms?
  • How engaged were students during the lab and model-building activities?