1. Energy and Equilibrium
Chapter 17 and 18
Energy and Equilibrium

2. Energy Profile for Exergonic Rxn
Illustrate graph and label reactants, products, E, Ea = activation energy and show how a catalyst affected the activation energy. (p534 and p541)

3. Energy Profile for Endergonic Rxn
Illustrate graph and label reactants, products, ∆E, Ea = activation energy and show how a catalyst affected the activation energy.

4. Equilibrium
Equilibrium – a dynamic condition in which two opposing changes occur at equal rates in a closed system.
Ex. Inside a department store, the number of people on the up escalator is equal to the number of people on the down escalator.

5. Le Chatelier’s Principle
Le Chatelier’s principle provides a means to predict the influence of stress factors on equilibrium systems.
In a reversible chemical rxn, the rxn can move forward or backwards.
A + B <--> C + D

6. Le Chatelier’s Principle
Le Chatelier’s principle states that if a system at equilibrium is subjected to a stress, the equilibrium is shifted in the direction that tends to relieve the stress.

7. Changes in Pressure Pressure Changes
Note: pressure doesn’t affect solids or liquids.
Increase in Pressure – shift to reduce # gas molecules
Decrease in Pressure – shift to increase # gas molecules

8. Changes in Concentration
A + B <--> C + D
Increase in concentration of a reactant – shift to producing more product (to use up reactant)
Ex. Increase in concentration of A, equil shifts to produce more of C and D.
2. Decrease in concentration of a reactant – shift to reverse reaction to make more of reactant
Ex. Decrease in concentration of B, equil shifts to produce more of A and B.

9. Changes in Temperature
A + B <--> C + Energy
Ex. N2 + 3H2 <--> 2NH kJ
Increase in temperature, equil shifts to use up heat (energy)
Ex. If the temp inc in the above rxn, then the equil shifts to form more nitrogen and hydrogen.
2. Decrease in temperature, equil shifts to form more energy
Ex. If the temperature decreases in the above rxn, then the equil shifts to form more ammonia (NH3).

10. Prac. P568 #5