Home > chemistry > See eff effin sees

See eff effin sees

As my wife will attest, I have a horrible, horrible memory. This isn’t just important dates and anniversaries, which with the exception of my mother’s birthday I always seem to remember, but encompasses a lot of stuff that I supposedly have learned throughout the years. Case in point, I was rereading Carl Sagan’s Billions and Billions the other day and couldn’t remember a great portion of a chapter that I know I’ve already read. The chapter talks about the hole in the ozone layer, how it was formed, and what the effects of it are. Despite being wholly depressing, it was also extremely interesting to find out more details about something that has become much more prevalent and part of the collective psyche of the world in the last few years.

Get your hard hats out for this one, Skippy, because I’m about to drop some chemistry on you.

Most of the time, when we talk about oxygen, we’re referring to oxygen the molecule versus oxygen the atom. The molecule oxygen is made up of two oxygen atoms (O2); ozone is made up of three oxygen atoms (O3). Oxygen molecules are fairly stable but will break apart into two separate oxygen atoms when reacting with some form of energy.  Ozone is less stable than oxygen molecules but more stable than oxygen atoms. When a lone oxygen atom meets up with an oxygen molecule, they will pair up and form ozone.

O2 + Energy -> 2O

O2 + O + M -> O3 + M

The M stands for some sort of catalyst and is necessary to bind the O2 and  O together. This is why the smell of ozone is often associated with electrical devices. Electricity passing through the air will provide the energy necessary to break apart the oxygen.

This seems like good news for the ozone layer. The energy from UV rays provided by the sun is more than enough to break up the O2 so we should be constantly generating O3 in the upper atmosphere, since O3 becomes more stable at lower temperatures and pressures. The problem with this is that ozone can be broken up far easier than it can be created. All you need is another catalyst, like chlorine, and the upper atmosphere is filled with chlorine.

CFC is a generic term for a chemical compound involving carbon (that’s the last C) fluorine (that’s the F) and/or chlorine (that’s the first C), it stands for chlorofluorocarbon. When CFCs were first used, they were seen as a miracle compound. They had a number of important uses; the most prevalent use was in refrigerators, replacing the toxic ammonia or sulfur dioxide that was previously used, but were also eventually used in aerosols, cleaning agents and Styrofoam. There was no noticeable downside to them. They weren’t dangerous to humans in any way, shape or form. At least that they knew about at the time. The problem is that when CFCs are released into the atmosphere, they hang around for quite a while before reaching the upper stratosphere and the ozone layer.

Once they reach the upper atmosphere, the CFCs hang around for a couple of dozen years before good old Mr.Sun tears them into pieces. This results in lots of Cl atoms floating around. As I said before, chlorine is a great catalyst to break up O3, so once wrenched apart from its carbon and fluorine brethren it becomes a veritable home wrecker to the happy little ozone family. It goes down like this:

O2 + Energy (in the form of UV light) -> 2O

2CL + 2 O3 -> 2ClO + 2 O2

2ClO + 2O -> 2Cl + 2 O2

The net result of this is:

2 O3 -> 3 O2

Once it’s done with its business, the chlorine is left unchanged and is free to repeat the process again and again. And again and again and again and again.  Eventually the Cl will drift down from the upper atmosphere and make its way back to the surface of the Earth, but not before going through this whole process about 100,000 times.

If one chlorine atom can do that much damage, imagine what a large chunk of it can do. How large of a chunk, you may ask, well, at peak production, we were doling out CFCs at the rate of a million tons per year. Luckily, we’ve since cut back enormously on our CFC production.

You’ve got to hand it to DuPont for a big portion of that. At the start of the whole ‘depletion of the ozone layer’ debate, they were gearing up to be the evil nature hating conglomerate a la Giovanni Ribisi in Avatar, and with good reason. They were making $600 million per year on CFCs. They wanted to run their own tests to determine what exactly the danger was. No doubt, their finding s would turn up no ill effects. Once they were faced with the facts and a number of nations agreed to reduce the emissions of CFCs, DuPont became an industry leader and vowed to stop production far earlier than the deadline that was being enforced. Good on them.

add to del.icio.us : Add to Blinkslist : add to furl : Digg it : add to ma.gnolia : Stumble It! : add to simpy : seed the vine : : : TailRank : post to facebook

Categories: chemistry Tags: , , , , ,
  1. No comments yet.
  1. No trackbacks yet.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: