Lesson Notes By Weeks and Term v4 - SHS 2
EQUILIBRIA
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EQUILIBRIA
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Subject: Chemistry
Class: SHS 2
Term: 2nd Term
Week: 6
Grade code: 2.1.2.LI.5
Strand code: 1
Sub-strand code: 2
Content standard code: 2.1.2.CS.2
Indicator code: 2.1.2.LI.5
Theme: PHYSICAL CHEMISTRY
Subtheme: EQUILIBRIA
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This lesson focuses on acid-base titration, a powerful quantitative analytical technique used to determine the unknown concentration of a solution. While it falls under the broad topic of Equilibria (as it involves a neutralisation reaction reaching an equivalence point), its practical application is in chemical analysis. In Ghana, this technique is vital in many industries, from ensuring the quality of fruit juices like FanYogo and Tampico, to testing the purity of medicines manufactured in Tema, and even monitoring the quality of our drinking water from the Weija Dam. By mastering titration, learners will gain a fundamental laboratory skill with wide-ranging real-world importance.
Part A: The Fundamentals of Acid-Base Titration
Titration is a laboratory method where a solution of a known concentration (the standard solution or titrant) is used to determine the concentration of an unknown solution (the analyte).
Key Terminology: Titrant: The solution of known concentration, usually placed in the burette. Analyte: The solution of unknown concentration, usually placed in the conical flask. Standard Solution: A solution whose concentration is known precisely. Equivalence Point: The point in the titration where the amount of titrant added is just enough to completely neutralise the analyte, according to the stoichiometry of the balanced chemical equation. This is a theoretical point. Endpoint: The point in the titration where a physical change, such as a colour change of an indicator, signals that the equivalence point has been reached. A good indicator has an endpoint that is very close to the equivalence point.
*Methyl Orange:* Red in acid (pH 4.4). Used for strong acid-weak base titrations. *Phenolphthalein:* Colourless in acid (pH 10). Used for strong acid-strong base or weak acid-strong base titrations.