
| Return to the coolnikz Index Page |
Catalyst
A catalyst is a substance that increases the speed of a chemical
reaction without being consumed by the reaction. For example, nitric oxide (NO)
is a catalyst in the breakdown of ozone (O3) in the upper atmosphere.
An oxygen atom
(O) will react with an ozone molecule form two oxygen molecules (O2),
but at a very slow rate. However, in the presence of nitric oxide, ozone is
quickly broken down with the following series of steps:
Step 1 - An oxygen atom combines with a molecule of nitric
oxide, forming a molecule of nitrogen dioxide (NO2):
O + NO --> NO2
Step 2 - A molecule of nitrogen dioxide combines with a
molecule of ozone, forming two molecules of oxygen and a molecule of nitric
oxide:
NO2 + O3 --> 2O2 + NO
Although the molecule of nitric oxide participates in the
reaction, it is not consumed by it and is available for additional reactions.

|