1. 4 Postulates of Kinetic Theory
Spherical molecules in constant, random straight-line motion
“Elastic” collisions
Point masses
No interactions
4 Postulates of Kinetic Theory

2. Gas that obeys all 4 assumptions of the kinetic theory all of the time
Gas that obeys all 4 assumptions of the kinetic theory all of the time. It doesn’t exist. It’s a model.
Ideal Gas

3. Most real gases obey the kinetic theory most of the time.

4. Which assumptions of the kinetic theory hold up?
Spherical molecules in random, straight-line motion
“Elastic” collisions
Which assumptions of the kinetic theory hold up?

5. Which assumptions of the kinetic theory break down?
Point masses
No interactions
Which assumptions of the kinetic theory break down?

6. When do the assumptions of the kinetic theory break down?
When the gas molecules are close to each other.
When do the assumptions of the kinetic theory break down?

7. When are the gas molecules close to each other?
At high pressure & low temperature.
When are the gas molecules close to each other?

8. When are the gas molecules far apart from each other?
At low pressure & high temperature.
When are the gas molecules far apart from each other?

9. How do the gas molecules act when they are far apart from each other?
Good!
How do the gas molecules act when they are far apart from each other?

10. What are the properties of gases?
Have mass
Take the shape & volume of their container
Compressible
Diffuse
Exert Pressure
What are the properties of gases?

11. Force/Area
Pressure

12. Collisions of the gas molecules with the walls of the container.
Pressure results from?

13. Pressure depends on? (microscopically)
# of impacts per unit time and force of each impact
Pressure depends on?
(microscopically)

14. Pressure depends on? (macroscopically)
# of gas molecules per unit volume
And
temperature
Pressure depends on?
(macroscopically)

15. A measure of the avg. kinetic energy of the particles of a substance.
Temperature

16. 4 variables needed to completely describe a gas-phase system?
Temperature
Pressure
Volume
# of moles
4 variables needed to completely describe a gas-phase system?

17. For a fixed mass and temperature, the pressure-volume product is a constant.
Boyle’s Law

18. PV = k where k = a constant
Boyle’s Law

19. P1V1 = P2V2
Boyle’s Law

20. Hyperbola – it’s an inverse relationship!
Graph of Boyle’s Law

21. Graph of Boyle’s Law, Pressure vs. Volume

22. Volume goes to ½ the original volume
Double the pressure

23. Volume goes to 1/3 the original volume
Triple the pressure

24. Volume goes to 2 X the original volume
Halve the pressure

25. Quadruple the pressure
Volume goes to 1/4 of the original volume
Quadruple the pressure

26. What does the graph of a direct relationship look like?

27. Kelvin: 0 K means 0 speed.
Which temperature scale has a direct relationship to molecular velocity?

28. Graph of Volume vs. Kelvin Temperature
It’s a direct relationship.
Graph of Volume vs. Kelvin Temperature

29. Math expression of Volume & Kelvin Temperature
V1/T1 = V2/T2
Charles’ Law
Math expression of Volume & Kelvin Temperature

30. What happens to the volume when the Kelvin temperature is doubled?
The volume doubles!
What happens to the volume when the Kelvin temperature is doubled?

31. What happens to the volume when the Kelvin temperature is tripled?
The volume triples!
What happens to the volume when the Kelvin temperature is tripled?

32. What happens to the volume when the Kelvin temperature is halved?
The volume is halved!
What happens to the volume when the Kelvin temperature is halved?

33. What happens to the Kelvin temperature when the volume is halved?
It’s halved!
What happens to the Kelvin temperature when the volume is halved?

34. Graph of Pressure vs. Kelvin Temperature
It’s a direct relationship.
Graph of Pressure vs. Kelvin Temperature

35. Math expression for pressure & temperature.
P1/T1 = P2/T2
Gay-Lussac’s Law
Math expression for pressure & temperature.

36. What happens to the pressure when the Kelvin temperature is doubled?
The pressure is doubled.
What happens to the pressure when the Kelvin temperature is doubled?

37. What happens to the pressure when the Kelvin temperature is halved?
The pressure is halved.
What happens to the pressure when the Kelvin temperature is halved?

38. What happens to the pressure when the Kelvin temperature is tripled?
The pressure is tripled.
What happens to the pressure when the Kelvin temperature is tripled?

39. What happens to the Kelvin temperature when the pressure is doubled?
The Kelvin temperature is doubled.
What happens to the Kelvin temperature when the pressure is doubled?

40. What is Avogadro’s Principle?
Equal volumes of gases at the same temperature & pressure have equal numbers of molecules.
What is Avogadro’s Principle?

41. These 2 boxes have the same:N2
These 2 boxes have the same:
Mass c) # of molecules
Density d) # of atoms

42. What is Dalton’s Law of Partial Pressures?
Ptot = P1 + P2 + P3 + P4 + …
What is Dalton’s Law of Partial Pressures?

43. He Ne Ar Kr Xe
Lightest is fastest!
At the same temperature, which of the following gases diffuses most rapidly?

44. He Ne Ar Kr Xe
Heaviest is slowest!
At the same temperature, which of the following gases diffuses most slowly?