1. EQUILIBRIUM

2. Most reactions go forward and backward!
Guess what…
Most reactions go forward and backward!

3. These reversible reactions come to a chemical equilibrium.

4. Equilibrium Occurs when the rate of the forward reaction is equal
to the rate of the backward reaction

5. Applications of Equilibrium:
Phase Changes
Saturated Solutions
Acids/Bases
Chemical Reactions

10. Occurs when the rate of the forward reaction is equal
Equilibrium
Occurs when the rate of the forward reaction is equal
to the rate of the backward reaction

11. How fast or slow a reaction occurs
Reaction Rate
How fast or slow a reaction occurs

12. Molecules must collide in order to react
Collision Theory
Molecules must collide in order to react

13. Reactions with a HIGH Ea proceed at a SLOW rate.

14. 2 HI  H2 + I2

16. Equilibrium Constant (Keq)
A measure of how far a reaction goes to the right

17. [ ] = concentration

18. Keq > 1 More products than reactants Keq < 1 More reactants than products

19. Once a reaction reaches equilibrium can it ever change??
YES!!! All it takes is a change in either the forward or reverse rates.

20. (and therefore changes
What changes rxn rate
(and therefore changes
the equilibrium):
Concentration
Pressure
Temperature

21. Le Chatelier’s Principle
If changes are made to
a system in equilibrium,
the RXN will shift in
the direction that will
reduce the change

22. Concentration If substance is added, the rxn will shift away from
that side;
If substance is removed, the rxn will shift towards that side

23. If pressure is increased, the rxn will shift to the
side that will produce
fewer molecules
(compare moles of gas)

24. Increased temp will shift the rxn to the side that absorbs heat
Temperature
Increased temp will shift the rxn to the side that absorbs heat