equilibrium

• What is a reversible reaction?

  Products can react to form original reactants
• What does the equation A+B <-> C+D represent?

  Forward reaction is endothermic
• What does the equation C+D <-> A+B represent?

  Backward reaction is exothermic
• What happens to energy in a reversible reaction?

  The same amount of energy is transferred both ways
• What is dynamic equilibrium?

  Rates of forward and reverse reactions are equal
• What occurs at dynamic equilibrium in a closed system?

  • Reactants convert to products
  • Products convert back to reactants
  • Rates of both processes are equal
  • Overall amounts of reactants and products are constant
• Can the amounts of reactants and products be equal at dynamic equilibrium?

  No, they can be in any ratio
• What factors can change the ratio of reactants and products at equilibrium?

  Conditions of the reaction
• How does the progress of a reaction change from start to dynamic equilibrium?

  • Amount of A+B: high, decreasing, constant
  • Frequency of collisions A+B: high, decreasing, constant
  • Rate of forward reaction: high, decreasing, equal to reverse
  • Amount of C+D: zero, increasing, constant
  • Frequency of collisions C+D: none, increasing, constant
  • Rate of reverse reaction: zero, increasing, equal to forward
• What do reaction conditions refer to?

  External environment of the reaction
• How can you change the conditions of a reaction in a closed system?

  • Change concentration of substances
  • Change temperature of the reaction vessel
  • Change pressure inside the vessel
• What does Le Châtelier's principle state?

  Closed systems counteract changes at equilibrium
• What happens when you change the concentration of products?

  • Decrease concentration: favours forward reaction
  • Increase concentration: favours reverse reaction
• What happens when you change the concentration of reactants?

  • Decrease concentration: favours reverse reaction
  • Increase concentration: favours forward reaction
• What happens when you change the temperature of the surroundings?

  • Increase temperature: favours endothermic reaction
  • Decrease temperature: favours exothermic reaction
• What happens when you change the pressure in a closed system?

  • Increase pressure: favours fewer molecules
  • Decrease pressure: favours more molecules