CFCs, damages the ozone

[Tim_Lou]

CFCs = Chlorofluorocarbons
CCl3F, or CCl2F2
they are stable, non-flammable, non-toxic chemicals...
it was widely used as the stuff in refrigerators in the past.

but there were some serious problems with this compounds:
when CCl3F escapes into the upper atmosphere, a reaction occurs, one of the Cl atom might "splits" off due to radiation, so, a Cl radical (a single atom) is released.
Cl + O3 --> O2 + ClO
this reaction leads to the destruction of ozone layer.
however, something more serious happens:
ClO + O --> O2 + Cl (radical)
(notice that the oxygen radical comes from O3 <--> O2 + O, ozone is being formed and destroyed by this reversible ractions)
notice that the Cl radical comes back! and its ready to attack again!
it acts as a catalyst in a way! one molecule of Cl radical can destroys tons of ozone molecules.......

well, is it non-stoppable? no, it reactions with some other substances in the atmosphere... one of them is:
ClO + NO2 --> ClONO2
(since ClO and NO2 are both radicals)
and
CH4 + Cl --> HCl + CH3
since this chemical is so dangerous to our atmosphere, it was reduced in production... laws are passed... well, thats not the focus here...

[TINNY]

why is the usage of CFCs for cooling damages the ozone. i thought it remains in a concealed place.

[Tim_Lou]

there could be possible leakage of these chemicals in the gas phase....
and people didnt realized its damage to ozone before serious results were observed...... such as the whatever hole over the Antarctica region.

there is sort of a seasonal ozone hole in the region, since the ClONO2 reactions occus when there are available surfaces, and during winter, water freeze in the upper atmosphere, ClONO2 reacts with some other stuffs in the atmosphere and ClO are released, which does damage to the ozone....

for details, take a look at http://www.atm.ch.cam.ac.uk/tour/part3.html

[TINNY]

and before they didnt really its damage to ozone before serious results were observed......

don't understand

the leakage is insignificant as far as i know

[Tim_Lou]

fixed that....

[Tim_Lou]

found from http://www.biospherical.com/nsf/student/answers.html
"8. What are CFCs?
Any of several organic compounds composed of carbon, fluorine, chlorine, and hydrogen. Some CFCs are manufactured under the trade name freon. Developed during the 1930s, CFCs found wide application after World War II. These "halogenated hydrocarbons" have been used extensively as aerosol-spray propellants, refrigerants, solvents, and foam-blowing agents. They are well-suited for these and other applications because they are nontoxic and nonflammable and can be readily converted from a liquid to a gas and vice versa.

9. Where do CFCs come from?
CFCs are man-made substances, which account for much of the damage to the ozone layer. CFCs were first used to clean electronic circuit boards, and as time progressed, were used in aerosols and coolants, such as refrigerators and air conditioners."

[Aki]

I think a while ago, I heard people say that the hole in the ozone layer near Antartica is becoming smaller all by itself. Did anyone else hear anything about that?

[pgrmdave]

I've heard that. I believe I heard that the world's production of CFC's had slowed down and the natural production of ozone was greater than the CFC's destruction.