- Physical Chemistry I
Spring 2013, Unique 52575
Lecture Summary, 12 April 2013
Collisions: So far everything we have done has been
for a single molecule colliding with the walls of the container
holding the system. What we really need, however, is
information about what happens when two separate molecules
collide. We therefore define a few new variables: 1) c(rel),
relative c; 2) z(coll), collision frequency (z(coll)
= (sigma(c(rel))P)/kBT); and 3) mean free path, lambda ( =
kBT/(sigmaP). NB: our result for mean free
path is slightly different from the result derived in M&S.
That is because I am sticking to describing average velocity as c,
rather than other options which M&S use interchangeably.