changing conditions

• What is Le Chatelier’s principle used for?

  To predict changes in equilibrium position
• What does the position of equilibrium refer to?

  Relative amounts of products and reactants
• What happens when a chemical system at equilibrium experiences a change?

  The position of equilibrium shifts to counteract the change
• What does shifting 'to the right' indicate in a reaction?

  More products are formed
• What does shifting 'to the left' indicate in a reaction?

  More reactants are formed
• What are the rules for predicting changes in equilibrium position using Le Chatelier’s principle?

  • Increasing reactant concentration shifts right
  • Increasing product concentration shifts left
  • Decreasing concentrations has opposite effects
• In the reaction N2(g) + 3H2(g) ⇌ 2NH3(g), what happens if [H2] is increased?

  Equilibrium shifts right towards NH3
• In the reaction N2(g) + 3H2(g) ⇌ 2NH3(g), what happens if [NH3] is decreased?

  Equilibrium shifts right to produce more NH3
• How do pressure changes affect gaseous equilibria?

  • Increasing pressure shifts to fewer gas molecules
  • Decreasing pressure shifts to more gas molecules
• In the reaction 2SO2(g) + O2(g) ⇌ 2SO3(g), what happens if pressure is increased?

  Equilibrium shifts right to reduce gas molecules
• How does temperature affect equilibrium shifts?

  • Increasing temperature shifts endothermic direction
  • Decreasing temperature shifts exothermic direction
• In the reaction N2(g) + O2(g) ⇌ 2NO(g) with ΔH = +180 kJ mol-1, what happens if the temperature is increased?

  Equilibrium shifts right to absorb heat
• In the reaction N2(g) + O2(g) ⇌ 2NO(g) with ΔH = +180 kJ mol-1, what happens if the temperature is decreased?

  Equilibrium shifts left to release heat
• What effect does adding a catalyst have on equilibrium position?

  No effect on position of equilibrium
• How does a catalyst affect reaction rates?

  It speeds up both forward and reverse reactions
• What are the conditions for industrial ethanol production?

  • Temperature: 300°C
  • Pressure: 60-70 atm
  • Catalyst: Phosphoric(V) acid
• What is the effect of high pressure (>70 atm) on ethanol production?

  Promotes more product formation
• What is the effect of low pressure (<60 atm) on ethanol production?

  More economical but decreases yield
• What is the effect of high temperature (>300°C) on ethanol production?

  Increases reaction rate but lowers yield
• What is the effect of low temperature (<300°C) on ethanol production?

  Increases yield but slows down reaction
• What are the considerations for industrial ethanol production conditions?

  • Maximize yield of ethanol
  • Ensure rapid reaction rate
  • Keep production costs low
• What is the selected temperature for industrial ethanol production?

  300°C
• What is the selected pressure for industrial ethanol production?

  60-70 atm