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.

[Monoxdifly]

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.

 

By "in the past", did you mean that there's no CFC in the newer refrigerators? So, can we use our refrigerators freely without feeling guilty now?

[exchemist]

By "in the past", did you mean that there's no CFC in the newer refrigerators? So, can we use our refrigerators freely without feeling guilty now?

Yes,CFCs were phased out a long time ago.

[Monoxdifly]

Yes,CFCs were phased out a long time ago.

So, what do we use in our refrigerators now? Are we back to Maxwell's Demon again?

[exchemist]

So, what do we use in our refrigerators now? Are we back to Maxwell's Demon again?

Hydrocarbons I think, and maybe still HFCs, though I may be out of date about that.

[fahrquad]

don't understand

 

the leakage is insignificant as far as i know

Chlorinated fluorocarbons were primarily used as a foaming agent in the manufacturing of plastics, particularly styrofoam.  The use of R-12 dichlorodiflouroethane in automobile cooling systems was relatively inconsequential by comparison but was unregulated.  R-22 was used in in home and commercial air conditioning and refrigeration.  I believe R-134a and R-410 are the primary refrigerants these days.  I have a can of R-12 and a hose kit for sale if anyone is interested.

[fahrquad]

The sticker inside my 10-ish year old refrigerator says R-134a.  I am not going to check my car or HVAC system right now.

[fahrquad]

Chlorinated fluorocarbons were primarily used as a foaming agent in the manufacturing of plastics, particularly styrofoam.  The use of R-12 dichlorodiflouroethane in automobile cooling systems was relatively inconsequential by comparison but was unregulated.  R-22 was used in in home and commercial air conditioning and refrigeration.  I believe R-134a and R-410 are the primary refrigerants these days.  I have a can of R-12 and a hose kit for sale if anyone is interested.

 

I will release the ozone eating R-12 into the atmosphere unless the governments of the world send me $15 in unmarked non-consecutive bills.  Bwah ha ha ha (in my best super-villain laugh).     

Edited February 10, 2019 by fahrquad

[Vmedvil2]

CFCs are definitely a cause of global warming that much I can say about the subject.

[exchemist]

The sticker inside my 10-ish year old refrigerator says R-134a.  I am not going to check my car or HVAC system right now.

I see that HFCs such R134a are now the subject of a phase-out plan, mandated by a 2016 amendment to the Montreal Protocol, due to their potency as climate change agents. More here: https://www.danfoss.com/en/about-danfoss/our-businesses/cooling/refrigerants-and-energy-efficiency/hfc-phase-down/montreal-protocol/

 

So HFCs are a great improvement as regards ozone depletion, but bad actors re climate change. 

 

You will see from the Danfoss link that ammonia, CO2 and hydrocarbons are candidate replacements, depending on the system. Ammonia is in fact already a traditional refrigerant fluid, used for over half a century in large refrigeration systems of the sort found in processing plants and refrigerated ships. The challenge is for the small systems (domestic, car aircon etc).