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: 1st Term
Week: 16
Grade code: 2.1.2.LI.4
Strand code: 1
Sub-strand code: 2
Content standard code: 2.1.2.CS.1
Indicator code: 2.1.2.LI.4
Theme: PHYSICAL CHEMISTRY
Subtheme: EQUILIBRIA
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This lesson introduces one of the most important concepts in chemistry: chemical equilibrium. Most chemical reactions we see in textbooks are written as if they go to completion (reactants -> products). In reality, many reactions are reversible, meaning products can turn back into reactants. Imagine a busy market like Makola or Kejetia; people are constantly entering and leaving, but the total number of people in the market at any given time might stay roughly the same. This is a "dynamic" balance. Chemical equilibrium is similar: the forward and reverse reactions are happening at the same rate, so the overall amounts of reactants and products do not change.
2.1 What is Dynamic Equilibrium?
A reversible reaction is a chemical reaction that can proceed in both the forward and reverse directions. We use a double arrow (⇌) to represent it. `Reactants ⇌ Products`
Dynamic Equilibrium is the state reached in a reversible reaction where the rate of the forward reaction is equal to the rate of the reverse reaction. At this point, the concentrations of reactants and products remain constant, not because the reaction has stopped, but because they are being formed and consumed at the same rate. Dynamic: The reactions are still occurring. Equilibrium: There is no net change in the amounts of reactants or products.
Example: The reaction between colourless dinitrogen tetroxide gas and brown nitrogen dioxide gas. `N₂O₄(g) ⇌ 2NO₂(g)` (colourless) (brown)