Chlorofluorocarbons and the ozone layer

Where is the ozone layer found

20-40km above earths surface

What is in the ozone layer

Relatively high concentration of the chemical ozone

What is the chemical symbol for ozone

O3

What does the ozone layer absorb

A large amount of UV radiation from the sun before it reaches the earths surface- protects living organisms from overexposure to UV

How does the ozone layer protect the earth from excessive UV exposure

Ozone molecule can absorb UV light turning back to an oxygen radical and an oxygen molecule

What happens in the stratosphere

UV radiation causes the double bond in oxygen molecules to break

O=O → O+O

Two oxygen radicals

What does the oxygen radical react with

An oxygen molecule

O + O2 → O3

What chemicals can cause ozone in the ozone layer to be broken down

Chlorofluorocarbons- haloalkanes

Why are CFCs very stable molecules

High bond enthalpies of carbon to halogen bonds

Relatively non-toxic

How can CFCs cause destruction to the ozone layer?

Make their way into the stratosphere, Once in stratosphere UV radiation causes a carbon-chlorine bond to break- photo dissociation

CFCL3→ CFCl2. + CL.

Propagation step 1:

Cl. + O3 → ClO. + O2

Propagation step 2:

ClO. + O → Cl. + O2

What can nitrogen oxide radicals do

Lead to destruction of ozone layer, formed by lightning and aircraft