Title: Gases and the Kinetic Molecular Theory
1Gases and the Kinetic Molecular Theory
2Speeds of gas molecules. For a single molecule.
Kinetic energy is KE ½ mv2 m mass v
velocity For a collection of gas molecules,
the average kinetic energy is
R ideal gas constant 8.314 J/K?mol T
temperature in Kelvin
3How fast do gas molecules move? Called the root
mean square speed of the gas.
in kg/mol
Equation gives speed in meters/second.
What is the rms speed of O2 molecules at room
temperature?
4Boltzmann Distributions
5Boltzmann Distributions and Molar Mass
6Boltzmann Distributions and Temperature
7Gas Diffusion
8Gas Effusion
9Grahams Law of Gas Effusion used for
determining molar mass of a gas
10Example A sample of ethane, C2H6, effuses
through a small hole at a rate of 3.6 x 10-6
mol/hr. An unknown gas, under the
same conditions, effuses at a rate of 1.3 x 10-6
mol/hr. Calculate the molar mass of the unknown
gas.