Fats And Oils SS3 Chemistry Lesson Note

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

1. identify the sources of fats and oils
2. Identify the properties of fats and oils.

INSTRUCTIONAL TECHNIQUES: 

• Identification, 
• explanation, 
• questions and answers,
• demonstration, 
• videos from source

INSTRUCTIONAL MATERIALS: 

• Videos, 
• loudspeaker, 
• textbook, 
• pictures

NOTE

FATS AND OIL

Fats and oils belong to a general group of compounds known as lipids. Fats are solids usually of animal origin while oils are liquids mainly from plants. Both are esters of the trihydric alkanol, propane-1,2,3-triol. Each molecule of propane-1,2,3,-triol is esterified with three molecules of fatty acids as follows.

Sources of Fats and Oils

• Fats and oils are found in both plant and animal sources.
• Plant sources include seeds, nuts, olives, and avocados.
• Animal sources include meat, fish, and dairy products.

Physical properties of fats and oil.

1. State at Room Temperature:

• Fats are typically solid at room temperature.
• Oils are liquid at room temperature.

2. Melting Point:

• Fats have a higher melting point due to their solid state.
• Oils have a lower melting point, remaining liquid at room temperature

3. Solubility:

• Fats and oils are insoluble in water.
• They are soluble in organic solvents like ether and chloroform.

4. Density:

• Fats are denser than oils due to their solid nature.
• Oils have a lower density because they are in a liquid state.

5. Odour and Flavor:

• Both fats and oils may carry specific odours and flavours based on their source and processing methods.

6. Colour:

• The colour of fats and oils can vary, ranging from clear to yellow or brown, depending on factors such as impurities, processing, and source.

Chemical properties of fats and oils

1. Fats and oils can undergo hydrolysis, a chemical reaction where they react with water in the presence of an acid or base to break down into glycerol and fatty acids.

   Triglyceride + 3H2O Glycerol + 3 Fatty Acids

2. Saponification is a reaction with a strong base (such as sodium hydroxide or potassium hydroxide) to produce soap and glycerol.

   Triglyceride  + 3NaOH Glycerol + 3 Soap Molecules

3. Polymerization:

• Under certain conditions, fatty acids in fats and oils can undergo polymerization, forming polymers. This process is often undesirable, as it can affect the quality of the fat or oil.

1. Isomerization reactions can occur in unsaturated fatty acids, leading to the conversion of cis-isomers to trans-isomers. Trans fats are associated with health concerns.

EVALUATION:   

1. Mention three sources of fats and oils
2. What is saponification, describe how saponification takes place
3. Identify 4 uses of fats and oils

CONCLUSION: The teacher commends the students positively