1. Stratospheric Ozone
Monday, February 26th, 2018

2. Good up high, bad nearby Troposphere: Stratosphere: 10 ppm O3
Thinnest layer of atmosphere, 80% mass, almost all H2O
0.04 ppm O3
Stratosphere: 10 ppm O3

4. *We’ll study health effects later this semester*
Characteristics of O3
Highly poisonous, strong odor, irritant, colorless gas
Chemically much more active than O2
Beneficial uses:
Purify water
Sterilize air
Bleaching certain foods (flour)
*We’ll study health effects later this semester*

5. O2 + UV light  2O 2O + 2O2  2O3 Formation of Ozone
Read the handout & summarize in your own words.
O2 + UV light  2O
2O + 2O2  2O3

6. Why do we care? Ozone layer blocks 95-99% of the incoming UV light
UV light disrupts, destroys complex molecules (life)  human health, animals, lots of crop damage
What’s causing the damage to the layer?

7. Amazing CFC’s (Chlorofluorocarbons)
Anthropogenic compound
Easily liquified! Odorless!
Relatively inert! (stable)
Non-toxic! Non-combustible!
Coolants, propellants, used in making styrofoam, industrial solvents
Because of its inertness, diffuses slowly, unchanged into stratosphere

8. Why is ozone thinning seasonal?
During sunless winter, polar stratospheric clouds (PSCs’s) form within vortex
This special cloud surface is ideal for “chlorine reserve compounds” (CFC’s, HCl, ClONO2) so they accumulate there

9. CF2Cl2 + UV light  cleaves Cl
Main Reactions
CF2Cl2 + UV light  cleaves Cl
Cl + O3  ClO + O2
ClO + O  Cl + O2
Catalyst – alters the rate of reaction without permanently being altered (used up) by that reaction, so it can react over and over again.
One molecule of Cl can potentially degrade over 100,000 molecules of O3 before it is removed from the stratosphere or becomes part of an inactive compound

10. Results of Ozone Depletion
Increased UV radiation reaching earth’s surface
Humans will have worse sunburns, more eye cataracts, & more skin cancers
Immune system suppression
Increase in acid deposition & photochemical smog in troposphere
Increased breakdown & degradation of paints, plastics, & outdoor materials

11. Results of Ozone Depletion
Increased UV radiation reaching earth’s surface
Lower yields of key crops (corn, rice, cotton, soybeans, wheat)
Decline in forest productivity (reducing CO2 uptake, enhancing global warming)
Reduction in productivity of surface-dwelling phytoplankton in oceans

12. Ozone Simulation – Part 1
Disclaimer: We will be tossing crumpled balls of paper around the classroom. It is important that you are VERY careful to not break anything or hurt anyone.
You will gather in groups of 2-3.
When a person in a group of 2 catches a ball, he/she must split off and go attach themselves to a single person or group of 2 people.
When a person in a group of 3 catches a ball, he/she must leave and go attach themselves to a single person or group of 2 people
When Miss Scott yells freeze, everyone must stop where they are, and link arms with their group members.

13. Ozone Simulation – Part 2
You will gather in groups of We will run through the simulation as we did in part 1, but with one change!
Chlorines (students holding the rulers) will look for groups of 3 students. He/she will grab one person from the group and take them “hostage” to the front of the classroom. Both students wait there.
Only a free student (group of 1) may rescue the hostage.
Once that happens, the chlorine is free to go and take another hostage.