CH353 - Physical Chemistry I
Spring 2013, Unique 52575

Lecture Summary, 12 April 2013

Molecular 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.