Mean Free Path and Reactions (Atmospheric Chemistry)

[sidnake]

Hi, I have an exam tomorrow for atmospheric chemistry and I was just going over some past papers. In one it asks the following question, "What is meant by "Mean Free Path"? How is this relevant to atmospheric chemistry.

My answer was as follows "The mean free path is the average distance a molecule travels before it undergoes collision with another molecule. Doubling the pressure, halfs the mean free path. This is relevant to atmospheric chemistry because the reduced pressure as altitude increases leads to an increased mean free path, which has an effect on the chemistry observed at different altitudes."

I was wondering what effect does the mean free path actually have on reactions present at different altitudes? I assume the higher the mean free path, the lower the reaction rate so at high altitudes only more reactive molecules will react? Anything else?

Thanks Alex

 

[Studiot]

Effect on chemistry?

Pressure of a gas is another word for concentration.

The rate of a chemical reaction depends upon the concentration of the participants so through your link to pressure is related to the mean free path.