SHS3 Chemistry · Semester 2 Week 12: Organic Functional Groups

Lesson notes

Learning Objectives

Indicator: 3.3.2.LI.2 - Explain structure, properties and uses of fats and oils in everyday life.

By the end of the lesson, learners can:

Write the general molecular formula for a fat molecule and identify the structural components (glycerol backbone and three fatty acid chains) of a triglyceride.
Draw and compare the structures of saturated and unsaturated fats, and explain how the presence of double bonds affects physical properties such as melting point and state at room temperature.
Write a balanced equation for the formation of a generalized glyceride from glycerol and long-chain fatty acids, and classify fats and oils as triglycerides.
Describe the four key reactions of fats and oils: alkaline hydrolysis (saponification), acid hydrolysis, catalytic hydrogenation, and rancidity, including conditions and products for each.
Apply the concept of iodine number to determine the degree of unsaturation in a fat or oil, and explain the uses of fats and oils in food, soap production, and margarine manufacturing.

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Curriculum details

Strand: Chemistry of Carbon Compounds (Strand 3)
Sub-strand: Organic Functional Groups (3.2)
Content standard: 3.3.2.CS.1 - Demonstrate knowledge and understanding of the concepts of organic chemistry to describe the structure and properties of alkanoic acid derivatives and lipids. 3.3.2.LO.1 Explain structure, preparation, properties of alkanoic acid derivatives and lipids as well as their uses in everyday life. 3.3.2.LO.2 Explain the structure, preparation, properties of polymers and their uses in everyday life.
Indicator: 3.3.2.LI.2 - Explain structure, properties and uses of fats and oils in everyday life.
Suggested placement: Semester 2, Week 12 (Week 32 of the year)
Our suggestion, laid out in curriculum order across three terms of twelve weeks. NaCCA does not fix the week, so follow your school's scheme of learning.
Curriculum reference: NaCCA curriculum document, p. 111

Exemplars (from the NaCCA curriculum)

Collaborative Learning:
- In gender-based groups where applicable, write general molecular formula for a fat molecule.
- Model the structures of saturated and unsaturated fat and state the differences in structure and physical properties between them.
- State some sources of fats and oils
- Explain why fats and oils are triglycerides and write an equation for the formation of a generalized glyceride molecule from long chain fatty acid and glycerol.
- Apply the concept of iodine number to determine the unsaturation of a fat.
- Discuss the reactions of fats and oils under the following headings: a. Hydrolysis using alkaline solution (saponification) or acidic b. Conditions or using enzymes c. Catalytic hydrogenation (margarine production) d. Rancidity
Experiential Learning:
- In small mixed-ability groups, carry out experiments to prepare soap using local materials and discuss ways of improving upon the quality of the soap prepared.
- Write a generalized structure for soap and outline the processes used in soap production.
Talk for Learning:
- Distinguish between soapy detergent and soapless detergents and describe how they act as grease-removing agents.
- State the advantages of a soapless detergent over soapy detergent.
Teaching and Learning Materials:
- * Molecular models * 250 ml beakers * Concentrated tetraoxosulphate (VI) acid * Ethanoic acid
- * Ethanol Worksheets on synthetic pathways suitable for the conversions of alkanol or carboxylic acids to alkanoic * Charts showing major commercial acid derivatives * Worksheets with a variety of carboxylic acid derivatives and scaffolding strategies for their reaction with nucleophilic reagents * Oil * Caustic soda * Wood ash or plantain peel ashes
- * Brine
- Heat source 500 ml beakers
- Test tube racks
- Test tubes * Heat source
- CHARTS
- use of esters
Assessment (3.3.2.AS.2). The document marks these depth-of-knowledge levels for this indicator: Level 3 Strategic reasoning.