Chapt. 6: Chemical Equilibrium

1. The Equilibrium Condition

1.1. How a reaction reaches equilibrium

1.2. Characteristics of chemical equilibrium

1.3. Equilibria are dynamic

2. The Equilibrium Constant

2.1. Law of mass action

2.2. Characteristics of the equilibrium expression

2.3. Equilibria in ammonia synthesis

2.4. Equilibrium position

3. Equilibrium Expressions Involving Pressures

3.1. Ideal gas law

3.2. Equilibrium partial pressures

3.3. Kp vs. K

4. The Concept of Activity

4.1. The reference state

4.2. For a gas, 1 atm

4.3. Definition of activity

5. Heterogeneous Equilibria

5.1. Phases: gas, solid, liquid

5.2. Heterogeneous Equilibria: between multiple phases

5.3. Equilibrium constant for heterogeneous equilibria

5.4. Activity of pure phases (solids or liquids)

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. Solving Equilibrium Problems

8. Le Châtelier's Principle

8.1. Effect of a change in conditions on equilibria

8.2. Effect of a change in concentration

8.3. Effect of a change in pressure

9. Equilibria Involving Real Gases

9.1. Non-ideality

9.2. How to correct Kp for non-ideality

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

11. K is meaningful only at equilibrium

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

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

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

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

13. Partial pressures sum to total pressure

14. Acitivity of pure solid or liquid = 1

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

16. ICE tables help organize equilibrium problems

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

18. You can do "math" with chemical equations

18.1. Adding c.e. means multiplying K

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

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

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

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

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

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

20. Activity coefficients correct for interactions between species