The Equilibrium Constant

• What is the equilibrium constant denoted as?

  K_c
• What type of reactions are reversible reactions?

  Reactions that can proceed in both directions
• In the reaction aA + bB ⇌ cC + dD, who are the reactants?

  A and B
• What does the equilibrium constant K_c indicate?

  Balance between reactants and products at equilibrium
• What does a large K_c value indicate about the reaction?

  The reaction favors the formation of products
• What does a small K_c value indicate about the reaction?

  The reaction favors the formation of reactants
• What does K_c being around 1 indicate?

  Both reactants and products are present in comparable amounts
• What does a large K_c value imply about the color of the reaction mixture?

  The mixture is mostly colorless
• What is the expression for K_c in the reaction 2NO₂ ⇌ N₂O₄?

  K_c = [N₂O₄] / [NO₂]²
• If [NO₂] = 0.2 mol/dm³ and [N₂O₄] = 0.8 mol/dm³, what is K_c?

  K_c = 20
• What is the purpose of an ICE table in calculating K_c?

  • Organizes concentrations at different stages
  • Stands for Initial, Change, Equilibrium
• In the reaction 2SO₃ ⇌ 2SO₂ + O₂, what is the initial concentration of SO₃?

  0.15 mol/dm³
• If the equilibrium concentration of O₂ is 0.05, what is x in the ICE table?

  x = 0.05
• What is the equilibrium concentration of SO₂ in the reaction 2SO₃ ⇌ 2SO₂ + O₂?

  0.10 mol/dm³
• How do you calculate K_c using equilibrium concentrations?

  K_c = (([SO₂]² × [O₂]) ÷ [SO₃]²)
• What is the calculated value of K_c for the reaction?

  K_c = 0.2 mol^-1 dm³
• What happens to K_c if the fraction is top heavy?

  We can swap the signs of the powers
• What are the units for K_c if the fraction is top heavy?

  mol^-1 dm³
• How does temperature affect K_c?

  K_c is temperature-dependent
• What happens to K_c if the forward reaction is exothermic and temperature increases?

  K_c decreases
• What happens to K_c if the forward reaction is endothermic and temperature increases?

  K_c increases
• In the Haber process, what happens to K_c when temperature is increased?

  K_c decreases
• How does changing the concentration of reactants affect K_c?

  K_c is not affected
• What does increasing the concentration of reactants do to the equilibrium position?

  Shifts equilibrium to the right
• What does increasing the concentration of products do to the equilibrium position?

  Shifts equilibrium to the left
• In the reaction PCl₅ ⇌ PCl₃ + Cl₂, what happens when PCl₅ concentration is increased?

  Equilibrium shifts to the right
• In the reaction PCl₅ ⇌ PCl₃ + Cl₂, what happens when Cl₂ concentration is increased?

  Equilibrium shifts to the left
• What is the role of catalysts in chemical reactions?

  Catalysts increase the reaction rate
• Do catalysts change K_c?

  No, K_c is only temperature-dependent
• How do catalysts affect the time to reach equilibrium?

  Catalysts help reach equilibrium more rapidly
• What are the factors affecting K_c?

  • Temperature
  • Concentration
  • Catalysts (do not affect K_c)