1. Equilibrian

2. NO + O3  NO2 + O2 Chemical Reactions: (what we know so far) 5 moles
How much ozone needed? How much products?

3. NO + O3  NO2 + O2 Chemical Reactions: (what we know so far)
1 bond broken, requiring 250 kJ
1 bond formed, releasing 300 kJ
What do we know about this reaction?

4. NO + O3  NO2 + O2 Chemical Reactions: (what we know so far)
When lots of NO and O3 are present, there are lots of collisions between them, so the reaction happens ___.
As time goes on, there is less NO and O3 so the rate will ____.

5. NO + O3  NO2 + O2 Chemical Reactions: (what you may not know)
When NO2 and O2 collide they can react with each other and turn back in to NO and O3!!!
Reactions that do this are known as reversible reactions (they can proceed in both directions)

6. Equilibrium: 20 people / min Scenario 1:
People come off the mountain at a faster rate than they go up.

7. Equilibrium: 20 people / min Scenario 2:
People come off the mountain at a slower rate than they go up.

8. Equilibrium: 20 people / min 20 people / min Scenario 3:
People go up the mountain at a the same rate as they go up.

9. Equilibrium:
Equilibrium has been achieved !!!

10. What is chemical equilibrium???
Replace the chair lift with reactants  products
H2 + I2  2HI
If at some point, rate = 2 M/sec
Replace the slopes with products  reactants
2HI  H2 + I2
and rate = 2 M/sec
Equilibrium: The point when the rate of the forward rxn is the same as the rate of the reverse rxn.

11. Equilibrium:
What is chemical equilibrium???
Once at eqm:
H2 + I2 ↔ 2HI
[H2], [I2] and [HI] remain constant!!!
Equilibrium: The point when the rate of the forward rxn is the same as the rate of the reverse rxn.

12. How reactions reach eqm:
Graph these rates simultaneously …
Time
Rate up mtn.
Rate down mtn.
20 ppl/min
1 ppl/min
15 ppl/min
5 ppl/min
12 ppl/min
8 ppl/min
10 ppl/min
Equilibrium:
How reactions reach eqm:
Mtn. opens
Reactions don’t start out with eqm between reactants and products, so how does it happen?
1 hour later
2 hrs later
3 hrs later

13. How reactions reach eqm:
Graph these rates simultaneously …
How reactions reach eqm:
Mtn. opens
Reactions don’t start out with eqm between reactants and products, so how does it happen?
1 hour later
2 hrs later
3 hrs later

14. Equilibrium:

15. Equilibrium: Equilibrium Analogy Assignment:
Now that you know what equilibrium is and have heard Mrs. Allen’s skiing analogy, it can be a helpful exercise to come up with your own real life analogy to chemical equilibrium.
Directions: Try and think of a real-life situation, place, activity, game, etc. that could serve as an analogy to chemical equilibrium. Once you have an idea, complete the following: