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: 18
Grade code: 3.1.2.LI.4
Strand code: 1
Sub-strand code: 2
Content standard code: 3.1.2.CS.4
Indicator code: 3.1.2.LI.4
Theme: PHYSICAL CHEMISTRY
Subtheme: EQUILIBRIA
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This lesson explores electrolysis, a powerful process that uses electricity to drive chemical reactions that would not happen on their own. This is not just a theoretical concept; it is the foundation of major industries in Ghana and around the world. From the production of aluminium at the VALCO plant in Tema to the purification of gold mined in Obuasi and Tarkwa, and even the simple silver coating on the cutlery we use, electrolysis is at work. By understanding how electrolytic cells operate, we gain insight into how we can harness electrical energy to create valuable materials and products.
This topic builds upon our understanding of chemical bonding, ions, and redox reactions. While it falls under the broad sub-strand of *Equilibria*, our focus is on the dynamic process of electrolysis, which disturbs the ionic equilibrium in a solution to force a non-spontaneous reaction. A. What is Electrolysis?
Electrolysis is the chemical decomposition of a substance (an electrolyte) in its molten state or in an aqueous solution, by the passage of a direct electric current. Electrolyte: A compound that conducts electricity when molten or dissolved in water, due to the presence of mobile ions. Examples: NaCl, CuSO₄, H₂SO₄. Electrolytic Cell: The apparatus in which electrolysis is carried out. It converts electrical energy into chemical energy. This is a non-spontaneous process; it requires an external power source to happen. B. Components of an Electrolytic Cell
An electrolytic cell has four main components: Power Source (DC): Provides the direct current (e.g., a battery) that forces the reaction. The flow of electrons is in one direction only. Electrodes: These are rods, usually made of metal or graphite, that conduct electricity into and out of the electrolyte. Anode: The positive electrode. It is connected to the positive terminal of the power supply. Anions (negative ions) migrate to the anode. Oxidation occurs here. Cathode: The negative electrode. It is connected to the negative terminal of the power supply. Cations (positive ions) migrate to the cathode. Reduction occurs here. Electrolyte: The molten or aqueous substance containing mobile ions. Container/Beaker: Holds the electrolyte.
Mnemonic to Remember: PANIC: Positive Anode, Negative Is Cathode. OIL RIG: Oxidation Is Loss (of electrons), Reduction Is Gain (of electrons).