1. Gases and the Kinetic Molecular Theory

2. Speeds of gas molecules. For a single molecule. Kinetic energy is: KE = ½ mv 2 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

3. How fast do gas molecules move? Called the root mean square speed of the gas. What is the rms speed of O 2 molecules at room temperature? in kg/mol Equation gives speed in meters/second.

4. Boltzmann Distributions

5. Boltzmann Distributions and Molar Mass

6. Boltzmann Distributions and Temperature

7. Which moves faster? 1.O2 at 300 K 2.He at 300 K 3.same

8. Which moves faster? 1.O2 at 250 K 2.O2 at 300 K 3.same

9. Which has greater kinetic energy? 1.O2 at 300 K 2.He at 300 K 3.same

10. All the O2 molecules at 300 K move faster than all the molecules of O2 at 200 K. 1.true 2.false

11. Gas Diffusion

12. Gas Effusion

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

14. Example: A sample of ethane, C 2 H 6, 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.

15. It’s time to… guess my age!

16. What age am I turning? 1.40 2.42 3.44 4.46 5.48 6.50 7.52 8.54 9.56

17. Properties of Gases