1. Instructor: Dr. Jules Carlson
End of Chapter 2 – The Behaviour of Gases – Chapter 4.1 – Characteristics of Atoms and Light
CHM1111 Section 04
Instructor: Dr. Jules Carlson
Class Time: M/W/F 1:30-2:20
Monday September 19th

2. Kinetic Molecular Theory
The Kinetic Theory describes gases as a large number of small particles that are in constant random motion.
Movement not caused by static repulsions, but from collisions.
Movement is faster at higher temperatures.
At higher temperatures, molecules have more kinetic energy.

3. Speeds of Gases vs. Mass
Smaller gases have higher velocities for same kinetic energy because they have smaller masses.
Speeds of H2, CH4, and CO2 molecules at 300 K.

4. I>clicker Question
Which of the following statements is/are true:
F2 moves faster than N2 at the same temperature.
Gas movement speed increases with increasing temperature.
A container is filled with 3 g of CO2 and H2O. In this container the partial pressure of CO2 is greater than H2O.
Both (a) and (b)
Both (a) and (c)

5. Average Kinetic Energy
The distribution of kinetic energies is not symmetrical, so average kinetic energy and most probable kinetic energy are not the same.
Most Probable Ekinetic
Average Ekinetic
Distributions of Kinetic Energy are the SAME for all gases at a given temperature!!!

6. Kinetic Energy and Temperature
Note that in both expressions, both the most kinetic energy is directly proportional to temperature
To calculate kinetic energies at different temperatures, use the following:

7. Kinetic Energy Problem
Calculate the kinetic energy per mole for Ar at 127 ⁰C?

8. Rates of Gas Movement
Called root-mean-square speed

9. Root-mean-square problem
What is the root-mean-square speed of H2 molecules at 380 torr and at -23 ⁰C?

10. Diffusion and Effusion
Effusion: Process where molecules escape from a container into a vacuum.
Diffusion: Process where molecules move from a container into a new container with lower concentration.
Average rate of movement can be determined by root-mean-square speed equation.

11. Graham’s Law Practical Application:
Practical Application:
Separation of Uranium isotopes by effusion rates.

12. Graham’s Experiment It was shown that NH3 travels further than HCl.
The ratio of the rates related with the square root of their molar mass ratio.