1. Honors Chem Chapters 10, 11, and 12

2. Kinetic Molecular Theory (KMT) Molecules are constantly in motion and collide with one another and the wall of a container Particles move faster with increased temperature Gases are made of mostly empty space and just a few fast moving particles.

3. Properties of Gases Low Density Expansion Compressibility Fluidity Diffusion/Effusion

4. Nature of Gases Diffusion: spontaneous mixing of gases

5. Nature of Gases Effusion: gas particles spontaneously pass through a small opening

6. Graham’s Law of Diffusion (or Effusion) Smaller, lighter gas molecules move faster through the air than larger, heavier gas molecules. “Lighter, faster, farther”

7. Graham’s Law of Diffusion (or Effusion)

8. Graham’s Law: Rewritten r = rate MM= Molar Mass d = distance t = time light = lighter gas heavy = heavy gas

9. Kinetic Molecular Theory (KMT) Molecules are constantly in motion and collide with one another and the wall of a container Particles move faster with increased temperature Gases are made of mostly empty space and just a few fast moving particles.

10. Ideal Gas Ideal Gas: a gas that perfectly conforms to assumed gas behavior (doesn’t exist) Most gases are described using real conditions and variables

11. Variables of Gases (P) Pressure (V) Volume (T) Temperature (n) Amount of gas in moles

12. Pressure Measures: Force exerted by moving gas particle collisions with their container

13. Pressure Units Units: 1 atm (atmosphere) of pressure is the average pressure at sea level Important Conversions: 1 atm= 760 mmHg (millimeters of Mercury) = 760 torr = 101.3 kPa (kilo Pascals) = 14.7 psi (pounds per square inch)

14. Volume Measures: amount of space that a gas occupies Units: Liters (L) Important Conversions: 1 L = 1000mL

15. Temperature Measures: average kinetic energy of gas particles. Units: Kelvin (K) The Celsius scale is NOT used for gases because gases can still have kinetic energy at negative and 0 o C.

16. Kelvin Scale and Absolute Zero Absolute Zero = 0 Kelvin represents the temperature at which a gas has NO kinetic energy

17. Converting Temperature Important Conversions: o C + 273 = K K – 273 = o C

18. STP STP = Standard Temperature and Pressure Exactly 0 o C and 1 atm At STP, one mole of gas (6.02 x10 23 particles) occupies 22.4 L If a gas is not held at STP, then volume is recalculated

19. Gas Variables A variable is a factor that is liable to change. Pressure, temperature, and volume of a gas are liable to change. Pressure, volume, and temperature are interdependent. When variable changes, they all do.

20. The Combined Gas Law Relates pressure, temperature, volume, and moles of a gas Relates initial and final conditions Variables that do not change are constants and not included in the equation

21. The Combined Gas Law Equation The left side (1) represents the initial conditions of the gas The right side (2) represents the final conditions of the gas

22. Charles’ Law: Volume and Temp What changes? And How? Volume increases, temperature increases What stays the same? Pressure and moles are held constant (toss ‘em)

23. Charles’ Law: Equation Remember: Temperatures must be in Kelvin

24. Charles’ Law: Graph Direct Relationship: both variables increase together

25. Charles Law: Simulation

26. Charles’ Law: Video Demo

27. Charles’ Law : Example A gas sample at 25 o C and 752 mL is heated to 50 o C, what is the new volume?

28. Boyle’s Law : Pressure and Volume What changes? And How? When Pressure increases, Volume decreases What stays the same? Temperature and moles are held constant (toss ‘em)

29. Boyle’s Law : Equation Remember: Pressure units on both sides of the equation must be the same P 1 V 1 = P 2 V 2

30. Boyle’s Law: Graph Inverse Relationship: an increase in one variable with a simultaneous decrease in the other

31. Boyle’s Law: Simulation

32. Boyle’s Law: Video Clip

33. Boyle’s Law Example Q: A 1.0 L sample of gas is held at standard pressure, 1.0 atm. The pressure of the gas is reset to 152 mmHg. What is the new volume of the gas?

34. Gay-Lussac’s Law: Pressure and Temperature What changes? And how? As temperature of a gas increases, the pressure also increases What stays the same? Volume and moles are held constant (toss ‘em)

35. Gay-Lussac’s Law: Equation Pressure units on both sides of the equation must be the same Temperature must be in Kelvin

36. Gay-Lussac’s Law: Graph Direct Relationship: Both variables increase together

37. Gay-Lussac’s Law: Simulation

38. Gay-Lussac’s Law: Video Clip

39. Gay-Lussac’s Law: Example Q: A gas has a pressure of 0.370 atm at 50.0 °C. What is the pressure at standard temperature?