Equilibria

• What state do all reversible reactions reach?

  Dynamic equilibrium state
• What is the general reaction for the formation of ammonia?

  N2 + 3H2 ⇌ 2NH3
• What are the two features of dynamic equilibrium?

  1. Forward and backward reactions occur at equal rates.
  2. Concentrations of reactants and products stay constant.
• What does the term 'position of equilibrium' refer to?

  Composition of the equilibrium mixture
• What happens if the position of equilibrium favors the reactants?

  Equilibrium mixture contains mostly reactants
• What does Le Chatelier’s principle help determine?

  Effects of changing external conditions on equilibrium
• What does Le Chatelier’s principle state?

  Equilibrium shifts to oppose changes in conditions
• What happens to equilibrium if temperature is increased?

  Shifts in the endothermic direction
• What is the effect of increasing temperature on ammonia yield?

  Lower yield of ammonia
• What happens if temperature is decreased in a reaction?

  Shifts in the exothermic direction
• What is a compromise temperature used for?

  To balance yield and reaction rate
• What effect does increasing pressure have on equilibrium?

  Shifts towards side with fewer moles of gas
• What is the reaction for methanol production?

  CO (g) + 2H2(g) ⇌ CH3OH (g)
• What happens to equilibrium if pressure is increased in methanol production?

  Shifts towards the right for higher yield
• What happens if pressure is decreased?

  Shifts towards side with more moles of gas
• What occurs if the number of moles of gas is the same on both sides?

  No effect on position of equilibrium
• What is the effect of increasing pressure on reaction rates?

  May give a higher yield and faster rate
• What does a catalyst do to equilibrium?

  No effect on position, speeds up rate
• What are the industrial processes that rely on equilibrium?

  • Haber process
  • Contact process
  • Hydration of ethene
  • Production of methanol
• What is the temperature and pressure for the Haber process?

  T= 450°C, P= 200-1000 atm
• What is the temperature and pressure for the Contact process?

  T= 450°C, P= 1 or 2 atm
• What is the catalyst used in the Haber process?

  Iron
• What is the catalyst used in the Contact process?

  V2O5
• What is the reaction for the hydration of ethene?

  CH2=CH2 (g) + H2O (g) ⇌ CH3CH2OH(l)
• What is the temperature and pressure for the hydration of ethene?

  T= 300°C, P= 70 atm
• What is the catalyst used in the hydration of ethene?

  Concentrated H3PO4
• What is the reaction for the production of methanol?

  CO (g) + 2H2(g) ⇌ CH3OH (g)
• What is the temperature and pressure for the production of methanol?

  T= 400°C, P= 50 atm
• What catalysts are used in the production of methanol?

  Chromium and zinc oxides
• What does carbon neutral mean?

  No net annual carbon emissions
• What is required for an activity to be carbon neutral?

  No fossil fuels used for energy
• What is the importance of recycling unreacted reactants?

  • Improves overall yields
  • Reduces waste in industrial processes
• What is the general form of an equilibrium reaction?

  mA + nB ⇌ pC + qD
• What is the equilibrium constant expression for a reaction?

  Kc = [C]^p [D]^q / [A]^m [B]^n
• What is the unit of Kc for the reaction H2 + Cl2 ⇌ 2HCl?

  No unit
• How do you calculate equilibrium moles?

  Initial moles - moles reacted
• How do you calculate equilibrium concentrations?

  Moles / volume (in dm³)
• What is the Kc expression for the reaction N2 + 3H2 ⇌ 2NH3?

  Kc = [NH3]^2 / [N2][H2]^3
• What is the Kc expression for the reaction H2 + Cl2 ⇌ 2HCl?

  Kc = [HCl]^2 / [H2][Cl2]
• How is equilibrium concentration calculated?

  Concentration = moles / volume