QUIZ

• Spontaneous reaction


  A reaction that does occur under the given set of conditions
• Nonspontaneous reaction


  A reaction that does not occur under specified conditions
• Second Law of Thermodynamics


  • The state of entropy of the entire universe, as an isolated system, will always increase over time
  • Entropy can never be negative
• Entropy


  • A thermodynamic quantity used to measure how spread out or dispersed the energy of a system is
  • Used to describe if the process is spontaneous and can occur in defined direction or nonspontaneous and will occur the reverse direction
  • A measure of how random or disorder the system is
• When entropy is positive


  • Melting, evaporation and sublimation
  • If a reaction produces more gas molecules that it consumes
  • If there is no net change in the total number of gas molecules
• When entropy is negative


  • Deposition, solidification and condensation
  • If the total number of gas molecules diminishes
• Gibbs' Free Energy


  • Used to determine the direction of a reaction
  • ΔG < 0 means the reaction is spontaneous in the forward direction
  • ΔG > 0 means the reaction is nonspontaneous, spontaneous in the opposite direction
  • ΔG = 0 means the system is at equilibrium, no net change

  
• Gibbs Free Energy


  G = H - TS
• Chemical Equilibrium


  A condition in the course of a reversible chemical reaction in which no net change in the amounts of reactants and products occurs
• Le Chatelier's Principle


  • When factors that influence an equilibrium are altered, the equilibrium will shift to a new position that tends to minimize those changes
  • When a system experiences a disturbance, it will respond to restore a new equilibrium state
• Changes in concentration


  • If an additional reactant is added, equilibrium shifts right towards products
  • If product concentration is reduced, equilibrium shifts right to form more products
  • If additional product is added, equilibrium shifts left towards reactants
  • If reactants are removed, equilibrium shifts left

  
• Changes in pressure


  • Increase in pressure causes reaction to go towards direction that favors formation of smaller volume
  • Increase in pressure puts stress on product side if products take up more volume than reactants

  
• Changes in temperature


  • For endothermic reactions: Increasing temperature shifts equilibrium right, decreasing shifts left
  • For exothermic reactions: Increasing temperature shifts equilibrium left, decreasing shifts right

  
• Catalysts do not have an effect on equilibrium of the system. They just speed up chemical reactions and help achieve equilibrium faster.