University College - Chemistry Chem 112A Lecture 2: Linking pressure to molecuular movement and reaction rates
20 Jan 2017
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Document Summary
Objective: link pressure to molecular properties and introduce concepts that govern the speed of chemical reactions. Py = mvy (before) py = -mvy (after) Conservation of momentum states: the wall of the box experiences a change in momentum that is equal and opposite to the change in momentum of the particle, therefore p = 2mvy for the wall. Force on the wall = rate of change of momentum. Particle moves towards the wall, hits it and exerts a force, then bounces back. It will then hit the opposite wall, come back, and hit the shaded wall again. F = p/ t where p is how much momentum is transferred in a collision and t is the time between collisions. Force on the wall due to one molecule: Pressure = force applied/area on which it"s acting (l2)/ For n molecules all moving in the same direction with a distribution of speeds. Pressure is the feeling from molecules colliding with the wall.
