Ozone

Question 1

Where does Ozone get it’s name?

Answer 1

From Greek derivative “to smell” - has distinct smell

Question 2

ozone discovery timeline

Answer 2

• introduced to science in 1840 by Dr. C. Shoenbein
• 1845: ozone linked to oxygen
• 1863: ozone identified as O3
• 1872: existence in atmosphere confirmed
• 1870s to today: systematic observations

Question 3

How is ozone formed?

Answer 3

O2 + sunlight —> O + O
O + O2 —> O3

Question 4

What are the natural destructions of ozone?

Answer 4

• via UV radiation: O3 + UV –> O2 + O
• via interaction with chlorine (CL):
  CL + O3 —> CLO + O2
  CLO + O —> CL + O2
  CLO = chlorine monoxide

Question 5

Where is ozone primarily found?

Answer 5

stratosphere at 1 part per thousand

Question 6

How and when is ozone created in the troposphere?

Answer 6

-can be created in the troposphere when hydrocarbons react with nitrogen oxides
- not good, leads to bas air quality
- O3 can aggravate asthma, etc.

Question 7

Stratospheric Ozone

Answer 7

• good thing
• absorbs UV radiation
• ozone layer
• being depleted

Question 8

What is the ozone layer?

Answer 8

• high concentration of ozone in the stratosphere
• is 0.00005% total atmospheric volume

Question 9

Chlorofluorocarbon (CFCs) - composition, created for what and when, what was used prior

Answer 9

• single carbon, two chlorines, two fluorines
• created in 1928 as non-toxic, non-flammable refridgerant, trademarked as Freon
• prior we used ammonia, sulfur dioxide, and methyl chloride
• worldwide consumption in 1988 was at over 1 billion kgs

Question 10

Why are CFCs a problem?

Answer 10

1. CFCs dissolve in the sunlight
2. A single Cl molecule floats around until it attacks an O3 molecule, pulling an O off it
3. Chlorine atom and oxygen atom join to form chlorine monoxide
4. A free oxygen pulls the O off the chlorine monoxide
5. Once free, the chlorine atom is off to attack another ozone molecule

Question 11

For each 1% decrease in ozone, UV radiation increases ___%

Answer 11

2%

Question 12

Where is the greatest reduction in stratospheric ozone and why?

Answer 12

Antarctica due to combo of cold temperatures, formation of polar stratospheric clouds, and the Antarctic vortex

Question 13

Montreal Protocol (1986)

Answer 13

international treaty to reduce CFC emissions and other ozone-depleting chemicals

Question 14

What is the timeline of the Montreal Protocol

Answer 14

-1974: chemists Rowland and Molina presented evidence suggesting that breakdown of CFCs could destroy ozone
- initially criticized, but were invited to testify before Congress
- led to substantial funding to study problem
- 1976: National Academy of Sciences released report confirming hypothesis - US govt declared CFCs only be used in important things
- 1985: studies by British Antarctic Survey found “ozone hole”
- treaty has been revised about 7 times
- 1992: ozone hole began in northern hemisphere - pushed president Bush to accelerate US implementation of treaty
- replaced CFCs with HCFCs, which also deplete O3, so plan is for them to be phased globally by 2040

Question 15

What is the Ozone Hole?

Answer 15

• the reduction in the amount of ozone of stratospheric ozone every year over Antarctica in its springtime (and now Greenland)
• any area under 220 Dobson units

Question 16

Why is O3 reduction largely in Arctic/Antarctic regions?

Answer 16

• Antarctica winters have very strong circumpolar winds that isolate the atmosphere over Antarctica
• stratospheric clouds form, chlorine atoms attach themselves
• when sun returns to Antarctica in Spring (Sept), chlorine atoms are released, setting up ozone-destroying chain reaction that lasts 5-6 weeks, until ozone from lower latitudes can mix back into Antarctic atmosphere