How many chlorine atoms does it take to destroy 100000 ozone molecules in a stratosphere?

Answer 1

There's a good chance one could do it.

The problem is that chlorine can, under certain conditions (like those found in the stratosphere), break off from a molecule and form what's called a "free radical" ... a lone chlorine atom with an unpaired electron. The free radical symbol is a dot representing the unpaired electron, but unfortunately everything I do here to try to depict it where it should be (about halfway up) generates a string of gibberish, so I'm just going to have to use a period instead, thus: Cl.

Free radicals are highly reactive and will attach themselves to complete molecules, forming a larger (and unstable) free radical that then falls apart. In order to stabilize a free radical, it must run into another free radical, with which it can react to form a relatively inert stable molecule again.

In the stratosphere, there are a lot more ozone molecules than chlorine free radicals, so the most common thing that tends to happen is

Cl. + O3 -> Cl. + O2

Cl. is itself a free radical, and reacts with oxygen free radicals (present naturally in the stratosphere as a result of the breakup of oxygen molecules by UV light):

ClO. + O. -> Cl. + O2

This regenerates the chlorine free radical, which can then go on to catalyze the decomposition of another ozone molecule, starting the cycle again. One chlorine atom can therefore be responsible for the destruction of thousands of ozone molecules before it runs into a free radical killer such as another chlorine free radical:

Cl. + Cl. -> Cl2

Answer 2

One chlorine atom can destroy many ozone molecules in the stratosphere. This is because the chlorine atom acts as a catalyst in ozone depletion, breaking down multiple ozone molecules without being consumed in the process. Therefore, only a small amount of chlorine atoms are needed to have a significant impact on ozone destruction.