1. Gases and the Kinetic Molecular Theory

2. Speeds of gas molecules. For a single molecule. Kinetic energy is:
KE = ½ mv m = mass; v = velocity
For a collection of gas molecules, the average kinetic energy is:
R = ideal gas constant = J/Kmol
T = temperature in Kelvin

3. How 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?

4. Boltzmann Distributions

5. Boltzmann Distributions and Molar Mass

6. Boltzmann Distributions and Temperature

7. Gas Diffusion

8. Gas Effusion

9. Graham’s Law of Gas Effusion:
used for determining molar mass of a gas

10. Example:
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.