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59
• Irreversible Reactions are reactions which can proceed in one direction only.
• In this topic, we will be focusing on reversible reactions.
Dynamic Equilibrium.
• Dynamic Equilibrium is a state in a reversible reaction at which:
• The rate of the forward reaction is equal to the rate of the backward reaction.
• The concentrations of the reactants and products are constant/fixed.
• Dynamic Equilibrium occurs in a closed container/system.
• We often use the term “position of equilibrium” when talking about
equilibrium. The position of equilibrium can either shift to the left-hand side
(reactant side), or the right-hand side (product side).
• Le Chatelier’s Principle: this principle states that when a change is made to
the conditions of a system at equilibrium, the system automatically moves to
oppose the change. This allows us to predict the changes to the position of
equilibrium.
Factors affecting the position of equilibrium:
• Temperature
• Pressure (for gases only)
• Concentration.
(i) Temperature
• An increase in temperature favours the endothermic reaction, while a
decrease in temperature favours the exothermic reaction. For example,
• The forward reaction is exothermic, thus the backward reaction must be
endothermic.