Lesson Notes By Weeks and Term v4 - SHS 3
EQUILIBRIA
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EQUILIBRIA
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Subject: Chemistry
Class: SHS 3
Term: 2nd Term
Week: 15
Grade code: 3.1.2.LI.3
Strand code: 1
Sub-strand code: 2
Content standard code: 3.1.2.CS.1
Indicator code: 3.1.2.LI.3
Theme: PHYSICAL CHEMISTRY
Subtheme: EQUILIBRIA
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Good morning, class. Have you ever wondered why you can drink a slightly acidic fruit juice like orange or pineapple juice, and your body's internal environment doesn't become dangerously acidic? Or how the pH of the soil in our cocoa farms remains stable despite acid rain? The answer lies in special solutions called buffer solutions. These are the chemical "shock absorbers" that maintain a stable pH. Understanding buffers is not just for passing exams; it is crucial for understanding biology, medicine, agriculture, and many industries right here in Ghana, from the pharmaceutical companies in Tema to our food processing factories.
2.1 What is a Buffer Solution?
A buffer solution is an aqueous solution that resists a change in its pH upon the addition of a small amount of an acid or a base, or upon dilution.
Imagine you have a beaker of pure water with a pH of 7. If you add just a drop of strong acid, the pH might plummet to 3. If you add a drop of strong base, it might shoot up to 11. A buffer solution, however, would hardly change its pH in the same situation. 2.2 Composition of Buffer Solutions
For a solution to act as a buffer, it must contain two related chemical species: a "proton donor" (an acid) to neutralize any added base, and a "proton acceptor" (a base) to neutralize any added acid. These two species must not neutralize each other. This is achieved by using a weak acid-base conjugate pair.