1. Gas Laws
Chapters

2. Review Temperature Pressure Volume Average kinetic energy
Collisions of gas particles between each other and container walls
Volume
Amount of space

3. Ideal Gas Don’t exist Model to explain behavior of all gases
Make assumptions about some properties that good under certain conditions

4. Kinetic Molecular Theory
The particles in a gas are constantly moving in rapid, random, straight-line motion.
Gas particles have no volume compared to the volume of the gas.
No attraction between particles
All collisions are completely elastic

5. Gas Laws Boyle’s Law Charles’s Law Gay-Lussac’s Law Combined Gas Law
Avogadro’s Law
Ideal Gas Law

6. Boyle’s Law Relationship between pressure and volume
Constant Temperature
Mathematical relationships
As pressure is decreasing, volume is increasing
As pressure is increasing, volume is decreasing

7. Boyle’s Law V P
Inverse

8. Boyle’s Law
PV = constant
Temperature remains constant

9. Example
A 40 L sample of gas at 1atm of pressure is compressed to 10 L. What is the new pressure of the gas?
P1V1 = P2V2
(1atm)(40L) = P2(10L)
P2 = 4 atm

10. Example
The pressure of a 25 L sample is changed from 2 atm to 0.4 atm. What is the new volume of the gas?
P1V1 = P2V2
(2atm)(25L) = (0.4atm)V2
V2 = 125 L

12. Charles’s Law Relationship between volume and temperature
Constant Pressure
Mathematical relationships
As temperature is increasing, volume is increasing
As temperature is decreasing, volume is decreasing

13. Charles’s Law T V
Direct

14. Charles’s Law V/T = constant Temperature must be in Kelvin
Pressure remains constant
Temperature must be in Kelvin

15. Example
A 4L sample of gas at 300K is heated to 600K. What is the new volume?

16. Example
A gas occupying 45L at 27°C is cooled until its volume is 15L. What is the new temperature of the gas?

18. Gay-Lussac's Law Relationship between pressure and temperature
Constant Volume
Mathematical relationships
As temperature is increasing, pressure is increasing
As temperature is decreasing, pressure is decreasing

19. Gay-Lussac's Law T P
Direct

20. Gay-Lussac's Law P/T = constant Temperature must be in Kelvin
Volume remains constant (rigid container)
Temperature must be in Kelvin

21. Example
In a rigid container, a sample of gas at 1 atm and 300K is heated to 400K. What is the pressure at this temperature?

22. Example
A sample of gas at kPa and 27°C is heated until its pressure is 3.5atm. What is the new temperature?

24. Review
Boyle’s Law
Charles’s Law
Gay-Lussac's Law

25. Question
How often do only 2 properties of a gas change while the other remains constant?
Rarely
Need a gas law that incorporates all three properties (PTV) changing

26. Combined Gas Law
Combines Boyle’s, Charles’s, and Gay-Lussac's Laws together

27. Example
A gas at 5atm is heated and compressed from 10L at 100K to 5L at 200K. What is the new pressure?

28. Example
A gas at 2atm and 27°C occupies 10L of space. What is the new volume when it is cooled to STP?

29. Real Life

31. Review
1 mole of ANY gas occupies 22.4L of volume at STP

32. Avogadro’s Law
Relationship between the amount of gas and the volume of the gas
Mathematical relationships
As the amount of gas increases, volume increases
As the amount of gas decreases, volume decreases

33. Avogadro’s Law n V
Direct

34. Avogadro’s Law V/n = constant
Pressure and Temperature remains constant

35. Avogadro’s Law
Equal volumes of gas at the same Temperature and Pressure have the same number of particles
At the same temperature and pressure, which sample contains the same number of moles of particles as 1 liter of O2(g)?
A. 1 L Ne(g) B. 0.5 L SO2(g)
C. 2 L N2(g) D. 4 L H2O(g)

36. Review
Boyle’s Law
Charles’s Law
Gay-Lussac’s Law
Avogadro’s Law

37. All Together Now Constant
If we add Avogadro’s Law into the Combined Gas Law:
Constant

38. Ideal Gas Law
PV = nRT
R = Universal Gas Constant
Ideal Gases follow assumptions of the Kinetic Molecular Theory

39. Kinetic Theory of Gases
The particles in a gas are constantly moving in rapid, random, straight-line motion.
Gas particles have no volume compared to the volume of the gas.
No attraction between particles
All collisions are completely elastic

40. Ideal Gases When do real gases act most like an ideal gas?
High Temperature
Low Pressure
When do real gases act least like an ideal gas?
Low Temperature
High Pressure