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: 18
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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Welcome, future scientists and engineers! Today, we are exploring one of the most important concepts in chemistry: Chemical Equilibrium. Imagine the bustling Kejetia or Makola market. People are constantly moving in and out, buying and selling. Yet, from a distance, the overall number of people in the market looks roughly the same. This is a "dynamic" but "stable" situation. Chemical equilibrium is very similar. Most chemical reactions are reversible, meaning they can proceed in both forward and reverse directions. Equilibrium is the point where the rate of the forward reaction equals the rate of the reverse reaction, creating a stable, dynamic balance.
A. Dynamic Equilibrium and the Law of Mass Action
A reversible reaction is a reaction that can proceed in both the forward and reverse directions. We use a double arrow (⇌) to represent it.
Example: N₂(g) + 3H₂(g) ⇌ 2NH₃(g) *(Forward reaction: Nitrogen and hydrogen form ammonia)* *(Reverse reaction: Ammonia decomposes into nitrogen and hydrogen)*
Dynamic Equilibrium is reached when: The rate of the forward reaction is exactly equal to the rate of the reverse reaction. The concentrations of all reactants and products become constant (they don't change anymore). The reaction has not stopped! Both forward and reverse reactions are still occurring at the same speed.