50: Ozone Depletion Flashcards
When were chlorofluorocarbons (CFCs) aka freons discovered?
discovered in 1930 by chemist working for General Motors
What are chlorofluorocarbons (CFCs) aka freons?
- chemically stable
- odorless
- nonflammable
- non-toxic
- non-corrosive
- inexpensive to make
What are chlorofluorocarbons used for?
plastic foams, solvents, auto air conditioning, other refrigeration, medical sterilant, aerosols
What happened in 1974?
chemist Sherwood Rowland and Mario Molina proposed a mechanism of action of the CFCs
What is the mechanism of action of CFCs?
- CFC under the action of UV light can lose a chlorine atom
- that atom attacks the molecule of ozone which then becomes oxygen
- the Cl atom is not destroyed during this reaction and is ready to attack again
How long does each CFC molecule last for?
65-100 years
What can each Cl atom released do?
convert 100,000 molecules of O3 into O2
What are halons (CDCs)?
also ozone depleting substances, they are present in fire extinguishers
What occurred in the 1980s?
scientists in Antartica noticed abnormally low levels of ozone in the stratosphere during September-December
What season is in Antartica from September to December?
spring! (Seasons in Southern Hemisphere are inverted)
Is there an ozone hole?
there is NO such thing as an ozone hole
What is occurring to ozone?
what there IS, is a thinning of the stratospheric ozone layer
How is the thickness of the ozone column measured?
is measured in Dobson Units
How do they measure ozone?
use balloons, satellites, artificial satellites to capture ozone and do some chemical reactions
- also use optical devices and aircrafts
What is the thickness of the ozone hole?
according to NASA, it used to be the thickness of 3 pennies, in ozone hole, thickness is about one dime
