Subject: Basic Science
Topic: Acids and Bases
Duration: 40mins
Instructional Material: Unripe Fruits
Previous Knowledge: Pupils are familiar with Water Cycle
Objective: At the end of the lesson, pupils should:
- Define Acid and Bases
- List the uses of acids and bases
Content:
Acids are substances that turn blue litmus paper to red, they occur naturally in living things e.g. in unripe fruits, human stomach (HCl which helps in digestion of food; ascorbic acid (vit c) in orange juice, lactic acid in yoghurt and sour milk etc.
Properties of Acids
- It has a sour taste
- It turns blue litmus paper red
- Concentrated acids wear away (burn) the human skin
Uses of Acids
- Vinegar is used in preparing salad
- They are used in manufacture of fertilizers, paper, dye and plastics
- It is used in vehicle batteries
- Some naturally occurring acids are present in the foods we eat such as fruits and vegetables.
Bases
Bases are chemical substances that turn red litmus paper blue. Some bases occur in nature as solid mineral ores e.g. copper, zinc, iron ore etc.
Alkali is a base that is soluble in water e.g. caustic soda.
Uses of Bases
- Caustic soda is used for making soap
- Lime (calcium hydroxide) makes acid soils suitable for the growth of crops
- Some bases are used for manufacturing various product e.g. paper
- A suspension of magnesium hydroxide in water is called milk of magnesia and is used as a mild laxative i.e. a medicine thqt helps to empty the bowel.
- Some minerals such as iron, aluminium copper and zinc ores are very useful to human beings.
Presentation:
Step 1: Teacher revises the previous lesson with the pupils.
Step 2: Teacher introduces and explains the new topic to the pupils.
Step 3: Pupils are allowed to ask questions.
Step 4: Teacher writes notes under content on the board for pupils to copy.
Evaluation:
- What are the properties of an acid?
- List examples of a base
Conclusion: Teacher moves round for inspection, marking and correction of notes where necessary.