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Subject: Chemistry
Semester: 1
Period: 2
Week: 7
School Name:
Teacher’s Name:
Subject: Chemistry
Grade Level: Grade 12
Week & Period: Week 7, Period II
Date:
Topic: Hydrocarbon Derivatives – Alkanols (Alcohols) and Alkanals (Aldehydes)
Subtopics:
- Alkanols: sources, classification, nomenclature, structure, physical and chemical properties, uses.
- Alkanals: classification, nomenclature, structure, properties, laboratory tests.
Learning Objectives: By the end of this lesson, learners should be able to:
- Classify alcohols and aldehydes based on structure.
- Describe the physical and chemical properties of alkanols and alkanals.
- Name alkanols and alkanals using IUPAC nomenclature.
- Perform simple laboratory tests to identify functional groups in alcohols and aldehydes.
- Outline the uses of alcohols and aldehydes in daily life and industry.
Previous Knowledge:
Learners have studied hydrocarbons (alkanes, alkenes, alkynes, and benzene).
Instructional Materials:
- Molecular models for alcohols and aldehydes
- Laboratory reagents: Fehling’s solution, Tollen’s reagent, sodium metal
- Ethanol, methanol, formaldehyde samples
- Charts showing nomenclature examples
Anticipation (Warm-Up) – 5 minutes:
Ask learners: "What are the key differences between alcohol and water structurally?" Follow-up by introducing functional groups.
Building Knowledge (Main Lesson) – 25 minutes:
- Alkanols (Alcohols):
- General structure: R–OH.
- Classification: primary, secondary, tertiary alcohols.
- Physical properties: hydrogen bonding, solubility, boiling points.
- Chemical reactions: combustion, dehydration, oxidation (to aldehydes/ketones).
- Laboratory test: reaction with sodium (effervescence), Lucas test, oxidation test.
- Uses: disinfectants, fuels, solvents, beverages.
- Alkanals (Aldehydes):
- General structure: R–CHO.
- Nomenclature ends in -al.
- Reactivity: presence of carbonyl group, oxidation to acids.
- Laboratory test: Tollen’s reagent (silver mirror), Fehling’s solution (brick-red precipitate).
- Uses: perfumes, preservatives, synthesis of acids.
Learners’ Activities:
- Use molecular model kits to represent ethanol and methanal.
- Perform Fehling’s and Tollen’s tests on unknown samples.
- Classify given alcohols as primary, secondary, or tertiary.
Consolidation (Review and Assessment) – 10 minutes:
- Quick oral quiz: Define functional group of alcohol and aldehyde.
- Identify if samples are alkanols or alkanals based on structure.
Homework / Assignment:
- Research the industrial uses of methanol and ethanol.
- Write the balanced chemical reaction for oxidation of ethanol to ethanoic acid.
Notes – Detailed and Explained:
- Alkanols are organic compounds containing a hydroxyl (-OH) functional group. They are classified into primary, secondary, and tertiary based on the carbon atom attached to the hydroxyl group. Alcohols show hydrogen bonding, making them more soluble in water than alkanes of similar molar mass.
- Chemically, alcohols undergo combustion, dehydration to form alkenes, and oxidation to form aldehydes or ketones.
- Alkanals (Aldehydes) contain a carbonyl group bonded to at least one hydrogen. They are more reactive than alcohols due to the carbonyl group. They can be oxidized to carboxylic acids and are tested using Tollen’s and Fehling’s reagents.
Expanded Notes / Instructions:
- Emphasize safety in handling ethanol and methanol.
- Encourage learners to relate alcohols to real-world applications like antiseptics and fuels.
- Discuss social issues (e.g., alcohol abuse) as part of contextual learning.
Inclusive / Differentiation:
- Visual learning via structural diagrams.
- Hands-on practicals for kinesthetic learners.
- Peer teaching during classification activity.
Teacher’s Reflection (Post-Lesson Questions):
- Did learners correctly identify and name alcohols and aldehydes?
- Were students engaged in the experimental tests?
- Do learners understand the importance of functional groups in organic reactions?