CHEM357 Chapter Notes - Chapter 8: Mass Diffusivity, Ideal Gas, Mean Free Path

• School: University of Waterloo
• Department: Chemistry
• Course: CHEM357
• Professor: Elizabeth Meiering

Document Summary

Chapter 8 (6): the motions of biological molecules. Properties (e. g. motion) of molecules determines the macroscopic behaviour of substances. E. g. as mw , molecules move slower, diffusion is slower. E. g. as t , molecules move faster, pressure of a gas viscosity of a liquid . Simplest system is ideal gas: behaviour can be derived from first principles and can also describe other systems e. g. liquids and solids. Diffusion coefficient and molecular properties: sedimentation (centrifugation, electrophoresis, molecular motion and kinetic theory. < > = average u = speed u = velocity. Solution: urms = < u2 > = (3rt/m) . What is the urms for oxygen (mw 32. 0) at 20. 00 c? (478 m s-1) Gaseous molecules, urms ~ 100-1000 m s-1. Speed of sound is ~300 m s-1, Highway speed limit of 100 km/hr = 28 m s-1. Knowledge of distribution is essential for understanding. Kinetic energies < u2 > reaction kinetics: collisions < u >