CH301H - Principles of Chemistry I: Honors
Fall 2012, Unique 51390

Lecture Summary, 15 November 2012

Kinetic Model of Gasses: Now that we know how ideal gasses behave, we have to know how often and with what energy two molecules collide.  To do this, we imagined a box filled with molecules moving in the x direction and colliding with the walls of the box.  By calculating the total change in momentum that occurs with each collision, we worked out an expression for the root mean square speed, crms, of each molecule:

      crms = (3RT/(FW))1/2

This is a remarkable result because it describes the kinetic energy of a molecule (through its velocity) in terms of constants (3, R, FW), and an easily measured property, T