Gases Lecture 4 Diffusion & Effusion

Diffusion the gradual, spontaneous mixing of gases due to the positive change in entropy associated with the process Remember the cloud of chlorine gas floating around the room

Effusion process of gas molecules confined in a container with a hole in it passing through that hole spontaneously Two gases at the same temperature have the same kinetic energy remember that temperature is a measure of kinetic energy KE= ½ mv2 if KEA=KEB, then. . . ½ mAvA2 = ½ mBvB2 mAvA2 = mBvB2

another way of writing this equation would be. . . vA/vB = mB/mA because the rate of effusion depends only on the velocity at which the molecules in a gas are moving, the equation can be rewritten as. . . rate of effusion of A mB = rate of effusion of B mA the lower the mass of a gas, the faster the rate of effusion refer to page 388 of your book to see an example of an effusion problem