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Subject: Chemistry
Semester: 1
Period: 1
Week: 2
School Name:
Teacher’s Name:
Subject: Chemistry
Grade Level: Grade 12
Week & Period: Week 2, Period I
Date:
Topic: Separation and Purification of Organic Compounds
Subtopics:
a. Distillation
b. Crystallization
c. Chromatography
d. Filtration
e. Sublimation
Learning Objectives:
By the end of the lesson, learners should be able to:
- List and describe methods for separating organic mixtures.
- Demonstrate how each method is used and state the types of compounds for which they are applicable.
- Differentiate between physical and chemical means of purification.
Previous Knowledge:
Learners have encountered basic laboratory separation techniques in general chemistry.
Instructional Materials:
- Distillation setup
- Chromatography paper and solvent
- Samples for crystallization and sublimation
- Visual aids and charts
Anticipation (Warm-Up) – 5 minutes
Pose a question: “How can we separate a mixture of salt and sand? Or ink pigments?” This leads into discussion of methods of separation and purification.
Building Knowledge (Main Lesson) – 25 minutes
- Explain physical properties used in separation: boiling point, solubility, vapor pressure.
- Describe each method:
- Distillation: Separation based on boiling point differences. Useful for liquid-liquid mixtures (e.g., ethanol and water).
- Crystallization: Formation of pure crystals from a saturated solution by cooling or evaporation.
- Chromatography: Separation based on differential solubility and capillary action.
- Filtration: Mechanical separation of solid-liquid mixtures.
- Sublimation: Separation where a substance passes directly from solid to gas (e.g., iodine or naphthalene).
- Discuss advantages, limitations, and real-world examples.
Learners’ Activities:
- Watch or participate in demonstration of distillation or chromatography.
- Interpret chromatograms from sample experiments.
- Group presentation of one separation method.
Consolidation (Review and Assessment) – 10 minutes
- Quiz: Match method to application.
- Exit question: Why is chromatography useful in forensic science?
Homework / Assignment:
- Draw diagrams showing how distillation and chromatography are set up.
- Research and report on an industrial use of any one purification technique.
Notes – Detailed and Explained
- Distillation involves heating a liquid to produce vapor and then condensing that vapor to collect the purified liquid.
- Crystallization is ideal for purifying solids, especially from solutions. Cooling reduces solubility and allows crystals to form.
- Chromatography separates based on movement of components on a stationary phase, great for separating dyes and inks.
- Filtration is ideal for mixtures where solids do not dissolve in liquids.
- Sublimation works only for solids that vaporize without melting.
Expanded Notes / Instructions:
- Include safety tips for using heat and solvents.
- Emphasize the principles behind why each method works.
- Allow learners to compare the suitability of each method for given mixtures.
Inclusive / Differentiation:
- Assign mixed-ability groups for presentations.
- Provide printed summaries for those needing support.
- Use video resources for learners who benefit from audio-visual aids.
Teacher’s Reflection (Post-Lesson Questions):
- Were learners able to match techniques to scenarios?
- Did the demonstrations aid understanding?
- Which methods should be revised again with more depth?