Chapt. 6: Chemical Equilibrium

1. Equilibria Involving Real Gases

1.1. Non-ideality

1.2. How to correct Kp for non-ideality

2. "Stress" on an equilibrium shifts reaction in direction that minimizes change

2.1. Add reactant (R) or product (P): rxn shifts to consume it Remove R or P: rxn shifts to replace it

2.2. Decrease the volume: rxn shifts to the side with the smallest n

2.3. Treat energy as R or P to predict effect of T on K

3. Le Châtelier's Principle

3.1. Effect of a change in conditions on equilibria

3.2. Effect of a change in concentration

3.3. Effect of a change in pressure

4. Solving Equilibrium Problems

5. You can do "math" with chemical equations

5.1. Adding c.e. means multiplying K

5.2. Multiplying c.e. by n means taking K^n

5.3. Reversing c.e. means taking 1/K

6. Applications of the Equilibrium Constant

6.1. Predictions based on the equilibrium constant

6.2. Extent of reaction

6.3. Reaction quotient (Q)

6.4. Calculating equilibrium pressures and concentrations

7. Try to make x in the ICE table small. This simplifies the math!

8. ICE tables help organize equilibrium problems

9. Heterogeneous Equilibria

9.1. Phases: gas, solid, liquid

9.2. Heterogeneous Equilibria: between multiple phases

9.3. Equilibrium constant for heterogeneous equilibria

9.4. Activity of pure phases (solids or liquids)

10. Q describes the position of a rxn not necessarily at equilibrium

11. Acitivity of pure solid or liquid = 1

12. Activity coefficients correct for interactions between species

13. The Equilibrium Condition

13.1. How a reaction reaches equilibrium

13.2. Characteristics of chemical equilibrium

13.3. Equilibria are dynamic

14. Equilibria are dynamic but may be so slow that []s appear not to change

15. The Equilibrium Constant

15.1. Law of mass action

15.2. Characteristics of the equilibrium expression

15.3. Equilibria in ammonia synthesis

15.4. Equilibrium position

16. K is meaningful only at equilibrium

16.1. Can't be = 0 or 1/0

16.2. Large K (>>1) means products favored

16.3. Small K (<<1) means reactants favored

17. Equilibrium Expressions Involving Pressures

17.1. Ideal gas law

17.2. Equilibrium partial pressures

17.3. Kp vs. K

18. Partial pressures sum to total pressure

19. Activity is a way to compare the amount of a reactant or product to their standard state and make K unit-less

20. The Concept of Activity

20.1. The reference state

20.2. For a gas, 1 atm

20.3. Definition of activity