Reversible Reactions

• What is required for equilibrium to be reached in a reversible reaction?

  A closed system
• What does it indicate if there are more reactants than products at equilibrium?

  The equilibrium lies to the left
• What is the general representation of a reversible reaction?

  A + B ⇌ C + D
• What happens to the concentrations of reactants and products at equilibrium?


  They don't change
• What effect does cooling have on the reaction involving ammonium chloride?

  It favours the left reaction
• What effect does heating have on a reversible reaction?

  It favours the right reaction
• What is the relationship between endothermic and exothermic reactions?

  One direction is endothermic, the other is exothermic
• What is an example of an endothermic reaction involving copper sulfate?

  Hydrated copper sulfate
• What is an example of an exothermic reaction involving copper sulfate?

  Anhydrous copper sulfate + Water
• What does Le Chatelier's Principle state about changes in equilibrium conditions?

  The system tries to counteract the change
• What happens to the equilibrium when temperature increases?

  It shifts to favour the endothermic direction
• What happens to the equilibrium when temperature decreases?

  It shifts to favour the exothermic direction
• What effect does increasing pressure have on a reversible reaction?

  It shifts to the side with fewer gas molecules
• What effect does decreasing pressure have on a reversible reaction?

  It shifts to the side with more gas molecules
• What happens if the concentration of reactants increases?

  The system makes more products
• What happens if the concentration of reactants decreases?

  The system makes more reactants
• What are the key concepts of reversible reactions and equilibrium?

  • Equilibrium reached in a closed system
  • More reactants than products: equilibrium lies left
  • More products than reactants: equilibrium lies right
  • Concentrations of reactants and products remain constant at equilibrium
  • Changing conditions can shift equilibrium
• What are the effects of temperature and pressure changes on equilibrium?

  • Increasing temperature favours endothermic direction
  • Decreasing temperature favours exothermic direction
  • Increasing pressure favours side with fewer gas molecules
  • Decreasing pressure favours side with more gas molecules
• How does concentration change affect a reversible reaction?

  • Increasing reactants: makes more products
  • Decreasing reactants: makes more reactants