Where in the atmosphere is the ozone broken down by chlorofluorocarbons?

Answer 1

Man made chemicals like chlorofluorocarbons, bromofluorocarbons are depleters of the ozone layer. There is evidence that natural sources of bromides and chlorides from ocean spray and volcanos can contribute to the depletion of the ozone as well as the Chloro- and Bromo- fluorocarbons produced by Man. It is thought that these levels have been constant from the ocean and the "normal" ozone levels are in balance with this natural depletion. The simplified reactions are:

CFCl3 + hν -> CFCl2 + Cl

Cl + O3 -> ClO + O2

ClO + O3 + hv(?) -> Cl + 2 O2

In words:

• Chlorofluorocarbons undergo dissociation in the presence of sunlight to produce a chlorine ion molecule. This molecule combines with ozone to reduce it to oxygen and a ClO molecule.
• The ClO attacks another Ozone molecule producing atomic oxygen and a chloride ion. The recreation of the Cl ion and the reactive ClO lets the chlorine reform and participate through many cycles.

Only ozone (not oxygen) in our current atmopshere can absorb UV-B radiation which is very very harmful for all the living organisms when it is at elevated levels. Potential impacts are death to algae and phytoplankton... all surface life in eventually, diseases and cancer.

The fluorine in some of these compounds does not contribute to the destruction of ozone. Ozone cannot displace fluorine from whatever molecule it is joined to.

The largest player of solely Man's efforts to the depletion of ozone is the CFCs used late in the 20th century, and still being made in the third world. These compounds are so stable, they are only removed from the air in the "ozone layer".

The concentration of ozone at any point in the atmosphere, is the result of a balance between reactions that make ozone, the natural decay of ozone, and destruction of ozone by other compounds.

With the Montreal protocol to ban ODS (ozone depleting substances) releases the present atmospheric load of brominated and chlorinated substances should decrease in time.

Global warming and ozone depletion are not the same problem.

Aside: In preparing for nuclear war the USA removed all Freon cooling systems from its atomic bomb carrying ICBMs so the the ozone layer would not be affected during a missile strike.

The amount of ozone at any point is a balance of those three processes. Production / decay / consumption.

"ozone depleting substances" is more generic, since other chlorine- and bromine-containing molecules, which are produced by Man, have been found "up there" too.

Note that CFCs are not "produced by aerosols", but were intentionally manufactured for the purposes of refrigerant or aerosol propellant. Not too many countries are still making / using CFCs.

The amount of ozone in the atmosphere in any given volume is the summation of:

1. (+) photoproduction of oxygen into ozone.
2. (+) photoactivation and decay of N2O* into N2 and ozone.
3. (-) destruction of ozone with time.
4. (-) increase in rate of destruction by increasing temperature.
5. (-) destruction of ozone by water vapor.
6. (-) destruction of ozone by other compounds / catalysts.
7. (+/-) diffusion of ozone into or out of the volume being considered.

So thinning results from a reduction in 1 and/or 2, an increase in any of 3 thru 6, or 7 ozone bleeding out into other spaces (seen adjacent to the ozone hole).

Below is a link that talks about CFC chemistry, about halfway down the page.

This title is a typo that cannot be fixed. "ofcs" should be "cfcs"

See "How do CFCs destroy ozone?"

A CFC will decompose, releasing a chlorine atom. This atom will catalyze the 2Ozone --> 3Oxygen reaction, eating away at the ozone layer.

Answer 2

CFC contains the chlorine molecule which reacts with ozone (O3) molecule and splits into O2 & O molecules.

Dr Nitin H K

Answer 3

The ozone is broken down in the ozone layer. This layer is present in the stratosphere.

Answer 4

Chlorofluorocarbons are the reason for depletion of ozone layer. It reacts with ozone and breaks it into oxygen, which is useless to block UV radiations.