SCH4U - Chemistry 12 (2024-25) - A

SCH4U-25A

4-1: Summary

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Description

The following page summarizes important concepts learned in this lesson related to chemical equilibrium.

Page content

  • Chemical equilibrium is the point at which the concentration of the reactants and products in a reaction become constant
  • Dynamic equilibrium is the point at which the rates of the forward and reverse reactions are equal
  • Dynamic equilibrium can apply to chemical reactions, the ionization of weak electrolytes in solution as well as transitions between liquid and vapour states
  • When a stress is added to a system, the equilibrium is disrupted
  • A stress is any change in the conditions of a system (for example, changes in: temperature, concentration, pressure, etc.)
  • A shift in equilibrium implies that the forward or reverse reaction starts occuring at a faster rate than the other, a shift to the right means that the forward reaction occurs faster than the reverse, while a shift to the left means that the reverse reaction occurs faster than the forward
  • Le Chatelier's Principle states that if a stress is applied to a system at equilibrium, the system will adjust in a way to oppose that change. 
  • According to Le Chatelier's Principle:
    • an increase in concentration of a reactant shifts the reaction to the right, while an increase in product concentration shifts the reaction to the left
    • an increase in pressure shifts the reaction in the direction that produces fewer particles, while a reduction in pressure shifts the reaction in the direction that produces more particles
    • an increase in the temperature of a system will shift the reaction in the direction that absorbs heat (ie the endothermic direction) while a decrease in the system temperature will shift the reaction in the direction that releases heat