Chemical equilibrium

• What does dynamic equilibrium mean?

  Rates of forward and reverse reactions equal
• What happens to concentrations in dynamic equilibrium?

  Concentrations of reactants and products remain constant
• What factors can alter the position of equilibrium?

  Concentration, pressure, and temperature
• What does Le Chatelier’s principle state?

  Equilibrium shifts to reduce disturbance
• What happens to equilibrium when temperature increases?

  Equilibrium position shifts to the endothermic direction to reduce temperature
• What happens to equilibrium when pressure increases?

  Equilibrium position shifts to the side with less gas moles
• What happens to equilibrium when concentration is increased

  Equilibrium shifts to opposite direction to remove extra concentration
• What effect does a catalyst have on the position of equilibrium?


  No effect on equilibrium position
• What conditions affect the value of Kc?

  Concentration, pressure, and temperature
• What is the expression for Kc for the reaction 2[A] + 3[B] + [C] ⇌ [D] + 4[E]?

  Kc = $\frac{[D][E]^4}{[A]^2[B]^3[C]}$

  
• What are the units for Kc?

  mol^-1 dm^-3
• For what type of system is Kc relevant?

  Homogeneous systems in equilibrium
• What does Kc being greater than 1 suggest?

  Equilibrium shifts to the right

  
• What does Kc being less than 1 suggest?

  Equilibrium shifts to the left

  
• What effect does decreasing temperature have on Kc in an endothermic reaction?

  Kc decreases
• What effect does increasing temperature have on Kc in an endothermic reaction?

  Kc increases
• What effect does decreasing temperature have on Kc in an exothermic reaction?

  Kc increases
• What effect does increasing temperature have on Kc in an exothermic reaction?

  Kc decreases
• What are the compromise conditions

  • Maximum yield
  • Rate
  • Operational conditions(lower pressure is less dangerous)
  • Cost
  • Environmental factors