1.1 What is Chemistry?

http://www.ck12.org Chapter 19. Chemical Equilibrium

Lesson Review Questions

1. Describe the basis of Le Chatlier’s principle.


2. Is the value of the equilibrium constant changed with the addition or removal of reactant or product? If so,
   how? If not, why not?


3. Is the value of the equilibrium constant changed when the temperature is increased or decreased? If so, how?
   If not, why not?


4. How does the addition of an inert gas affect the equilibrium of a system?


5. Why does the addition of a catalyst have no effect on the equilibrium position?


6. The following reaction is allowed to reach equilibrium: CaCO 3 (s) +heatCaO(s) +CO 2 (g). Would the
   reaction shift left, shift right, or remain unchanged in response to each of the following changes:
   (a) Increasing the pressure by decreasing the volume at a constant temperature
   (b) Increasing the pressure by adding an inert gas at a constant temperature and volume
   (c) Increasing the temperature at a constant pressure
   (d) Adding a catalyst


7. The following reaction is allowed to reach equilibrium: CO(g) +H 2 O(g) +heat→CO 2 (g) +H 2 (g). Would
   the reaction shift left, shift right, or remain unchanged in response to each of the following changes:
   (a) Increasing [CO]
   (b) Decreasing [H 2 ]
   (c) Decreasing [H 2 O]
   (d) Increasing [CO 2 ]

Further Reading / Supplemental Links

• Chemical equilibria simulation: http://group.chem.iastate.edu/Greenbowe/sections/projectfolder/animationsind
  ex.htm


• (Curtin, Wahlstron and McCormick, 1991). NO2/N2O4 equilibrium experiment. Journal of Chemical Educa-
  tion 1991 68 (9), 781

Points to Consider

• When chemical equilibrium is achieved for a given chemical process, the rate at which the forward process
  occurs is the same as the rate at which the reverse process occurs. What factors do you suppose affect the rate
  at which equilibrium is achieved?


• Some chemical processes are spontaneous, while others are not. How do you suppose chemical equilibrium is
  related to whether or not a chemical process is spontaneous or not?


• Can you think of examples where a particular process is spontaneous under certain conditions (say tempera-
  ture) and nonspontaneous under other conditions?