2. When a chemical system at equilibrium is disturbed, the system shifts in a direction that minimizes the disturbance (the system will respond to relieve the stress and re-establish equilibrium).

3.  An increase in the concentration of a species will shift the equilibrium to the opposite side.  A decrease in concentration of a species will shift the equilibrium to the same side.

4. 

5.  An increase in pressure will shift the equilibrium to the side with fewer gaseous molecules. Nature can reverse the pressure increase by decreasing the number of collisions.  A decrease in pressure will shift the equilibrium to the side with more gaseous molecules. Nature can reverse the pressure reduction by increasing the number of collisions.

6.  42 32 11

7.  Volume changes are interpreted as pressure changes from Boyle’s Law. Decreasing the volume will increase the pressure and increasing the volume will decrease the pressure.  Increasing the volume causes the reaction to shift in the direction that has more moles of gas particles  Decreasing the volume causes the reaction to shift in the direction that has fewer moles of gas particles

8.  4 2 32

9. 

10. 

11.  Endo Exo Endo Exo Endo Exo Endo

12.  Adding similar ions will shift equilibrium  Addition of a substance containing an ion that is common to the equilibrium system will increase the concentration of that ion, and the equilibrium will shift to reduce the concentration of that ion

13. 

14.  Catalyst – a substance that increases the rate of a chemical reaction but is not consumed by the reaction  Catalysts lower the activation energy making it easier for reactants to get over the energy hump. Activation energy – amount of energy that must be absorbed by reactants before a reaction can occur; an energy hump that normally exists between the reactants and products. Activated Complex – point at which the reaction will go to completion or go back to reactants. Enthalpy ( Δ H) is the energy difference between the reactants and products  Exothermic reactions have a negative Δ H  Endothermic reactions have a positive Δ H

15.  A catalyst does not change the position of equilibrium; only how fast equilibrium is reached.  A catalyst does not change the value of K eq for a reaction; it affects only the rate of reaction