1. Gas Properties

2. Gasses A state of matter characterized by: A state of matter characterized by: Filling the container it occupies Filling the container it occupies Having a volume that is not fixed Having a volume that is not fixed Particles that have little or no intermolecular forces acting on them Particles that have little or no intermolecular forces acting on them Particles have freedom of motion Particles have freedom of motion

3. Pressure Pressure – Force per Area Pressure – Force per Area Atmospheric pressure is 14.7 lbs/in 2 Atmospheric pressure is 14.7 lbs/in 2 Pressure is caused by the force of molecules striking a surface Pressure is caused by the force of molecules striking a surface

4. Pressure Typical Units Include Typical Units Include Atmospheres (atm) Atmospheres (atm) Kilopascals (kPa) Kilopascals (kPa) Millimeters of mercury (mmHg) Millimeters of mercury (mmHg) Torr (torr) Torr (torr) 1atm = 101.325 kPa = 760 mmHg = 760 torr 1atm = 101.325 kPa = 760 mmHg = 760 torr

5. Temperature Relative measure of Relative measure of Translational energy Movement in a particular direction Vibrational Energy Rotational Energy If two substances are at the same temperature, no NET energy is transferred between them. If two substances are at the same temperature, no NET energy is transferred between them.

6. Temperature Scales

7. Temperature Conversions Convert 25°C to Kelvin Convert 25°C to Kelvin Convert 345K to Celsius Convert 345K to Celsius Convert -45°C to Kelvin Convert -45°C to Kelvin Convert 288K to Celsius Convert 288K to Celsius

8. Properties of Gases The properties of gases are interdependent. The properties of gases are interdependent. Pressure (P) Pressure (P) Volume(V) Volume(V) Temperature (T) Temperature (T) Amount (moles, n) Amount (moles, n) Changing one can affect the others Changing one can affect the others Exception - The amount of gas affects the other variables but the other variables do not affect the amount Exception - The amount of gas affects the other variables but the other variables do not affect the amount

9. Gas Laws

10. Animated Gas Lab http://www.grc.nasa.gov/WWW/k- 12/airplane/Animation/frglab2.html http://www.grc.nasa.gov/WWW/k- 12/airplane/Animation/frglab2.html http://www.grc.nasa.gov/WWW/k- 12/airplane/Animation/frglab2.html http://www.grc.nasa.gov/WWW/k- 12/airplane/Animation/frglab2.html Hold two variables constant Hold two variables constant Volume Volume Amount of gas Amount of gas What is the relationship between pressure and temperature? What is the relationship between pressure and temperature? As temperature increases, pressure increases As temperature increases, pressure increases Direct Relationship Direct Relationship

11. With Numbers A stoppered flask in a hot water bath is allowed to cool along with the bath. A stoppered flask in a hot water bath is allowed to cool along with the bath. Pressure (atm) Temperature (°C)

12. Pressure vs. Temperature Calculate the x-intercept Calculate the x-intercept When P = 0… When P = 0… That’s very close to -273 °C That’s very close to -273 °C

13. Pressure vs. Temperature To avoid having the x-intercept not at the origin… To avoid having the x-intercept not at the origin… We define absolute temperature – Kelvin We define absolute temperature – Kelvin K = °C + 273 K = °C + 273 This defines an absolute zero This defines an absolute zero Absolute zero - (0K) - the temperature where a substance is in its lowest possible energy state. Absolute zero - (0K) - the temperature where a substance is in its lowest possible energy state. Always use Kelvin in Gas Law Problems Always use Kelvin in Gas Law Problems

14. Pressure vs. Temperature P = (constant) x T

15. Racquet ball Liquid_Nitrogen_-_Racquet_Ball.avi Liquid_Nitrogen_-_Racquet_Ball.avi Liquid_Nitrogen_-_Racquet_Ball.avi Think of the ball as a container of gas – balls bounce because they have a pocket of gas inside Think of the ball as a container of gas – balls bounce because they have a pocket of gas inside Use liquid nitrogen to cool a racquet ball Use liquid nitrogen to cool a racquet ball What changes? What changes?

16. Plunger Fun Monitor the pressure in a container while the plunger is moved in and out. Monitor the pressure in a container while the plunger is moved in and out. http://www.grc.nasa.gov/WWW/k- 12/airplane/Animation/frglab2.html http://www.grc.nasa.gov/WWW/k- 12/airplane/Animation/frglab2.html http://www.grc.nasa.gov/WWW/k- 12/airplane/Animation/frglab2.html http://www.grc.nasa.gov/WWW/k- 12/airplane/Animation/frglab2.html What is held constant? What is held constant? Pressure? Pressure? Volume? Volume? Temperature? Temperature? Amount of gas? Amount of gas? What is the relationship between pressure and volume? What is the relationship between pressure and volume? As the volume increases, pressure decreases As the volume increases, pressure decreases Inverse Relationship Inverse Relationship

17. Pressure vs. Volume

18. Balloon and Vacuum Pump

19. Injecting Air Into a Sealed Container What is held constant? What is held constant? Pressure? Pressure? Volume? Volume? Temperature? Temperature? Amount of gas? Amount of gas? What is the relationship between pressure and amount of gas? What is the relationship between pressure and amount of gas? As the amount of gas increases, pressure increases As the amount of gas increases, pressure increases Direct Relationship Direct Relationship

20. Pressure vs. Moles (n) P = (constant) x n P = (constant) x n

21. Can Activity Put water in the soda can to cover the bottom surface. Put water in the soda can to cover the bottom surface. Heat the can on the hot plate until you can see steam. Heat the can on the hot plate until you can see steam. With the tongs, QUICKLY turn the can upside down and immerse it in the cold- water bath. With the tongs, QUICKLY turn the can upside down and immerse it in the cold- water bath. Record your observations. Record your observations.

22. Can Activity Explain your results in terms of P, V, n, and T. Explain your results in terms of P, V, n, and T. Where did all the water in the can come from? Where did all the water in the can come from? What do you think would happen if you did this experiment with a glass jar instead of a can? What do you think would happen if you did this experiment with a glass jar instead of a can? What do you think would happen if you did this experiment with an empty can? What do you think would happen if you did this experiment with an empty can? What do you think would happen if you did this experiment with twice as much water? What do you think would happen if you did this experiment with twice as much water?

23. Cold Balloons Submerge an inflated balloon in liquid nitrogen (-196°C) MIT_Physics_Demo_-- _Balloons_in_Liquid_Nitrogen.avi Submerge an inflated balloon in liquid nitrogen (-196°C) MIT_Physics_Demo_-- _Balloons_in_Liquid_Nitrogen.aviMIT_Physics_Demo_-- _Balloons_in_Liquid_Nitrogen.aviMIT_Physics_Demo_-- _Balloons_in_Liquid_Nitrogen.avi What is held constant? What is held constant? Pressure? Pressure? Volume? Volume? Temperature? Temperature? Amount of gas? Amount of gas? What is the relationship between temperature and volume? What is the relationship between temperature and volume? As the temperature decreases, volume decreases As the temperature decreases, volume decreases Direct Relationship Direct Relationship

24. Volume vs. Temperature

25. Two Equations to Rule Them All P = (constant) T at a constant V and n P = (constant) T at a constant V and n P = (constant) n at a constant V and T P = (constant) n at a constant V and T P = (constant) / V at a constant n and T P = (constant) / V at a constant n and T

26. Ideal Gas Law R = Universal Gas Constant R = Universal Gas Constant

27. Combined Gas Law If we have a sealed container If we have a sealed container The number of moles is constant The number of moles is constant

28. Practice Problems What is the pressure in kilopascals inside a 20.0L container filled with 8.92mol of hydrogen gas at 25°C? What is the pressure in kilopascals inside a 20.0L container filled with 8.92mol of hydrogen gas at 25°C?

29. Practice Problems A 50.0L cylinder of argon gas at 19.8 atm has a temperature of 19.0°C. What volume of air could it displace in a room at 0.974atm pressure at the same temperature? A 50.0L cylinder of argon gas at 19.8 atm has a temperature of 19.0°C. What volume of air could it displace in a room at 0.974atm pressure at the same temperature?

30. Practice Problems A 550mL balloon is placed in a Bell jar attached to a vacuum pump. The vacuum pump is accidentally reversed so that the pressure increases inside the Bell jar from 0.987atm to 3.50atm before the Bell jar explodes. What is the volume of the balloon in the Bell jar before the jar explodes? A 550mL balloon is placed in a Bell jar attached to a vacuum pump. The vacuum pump is accidentally reversed so that the pressure increases inside the Bell jar from 0.987atm to 3.50atm before the Bell jar explodes. What is the volume of the balloon in the Bell jar before the jar explodes?

31. Practice Problems A certain car tire has a volume of 29.0L. The maximum rated operating pressure is 80.0psi. The temperature of a hot tire can reach as high as 105°C on a race track. What is the maximum amount of gas that should be pumped into the cold tire to ensure it doesn’t burst in the middle of a race? (1atm = 14.7 lbs/in 2 ) A certain car tire has a volume of 29.0L. The maximum rated operating pressure is 80.0psi. The temperature of a hot tire can reach as high as 105°C on a race track. What is the maximum amount of gas that should be pumped into the cold tire to ensure it doesn’t burst in the middle of a race? (1atm = 14.7 lbs/in 2 )

32. Practice Problems What mass of nitrogen is in a cylinder with a volume of 3.25L and a pressure of 15500 mmHg at 25°C? What mass of nitrogen is in a cylinder with a volume of 3.25L and a pressure of 15500 mmHg at 25°C?

33. Methanol/air fires can burn at temperatures as high as 1900°C. After shooting an 18.9L methanol rocket down the hall, it is quickly stoppered to seal the remaining gas in the container. What is the pressure inside the container once it cools back down to room temperature? Assume that atmospheric pressure is 1.00atm. Methanol/air fires can burn at temperatures as high as 1900°C. After shooting an 18.9L methanol rocket down the hall, it is quickly stoppered to seal the remaining gas in the container. What is the pressure inside the container once it cools back down to room temperature? Assume that atmospheric pressure is 1.00atm.

34. The typical pressure in Boone is around 670 torr. Opening shampoo after driving from Winston-Salem (where the typical pressure is around 740torr) to Boone is occasionally a slightly hazardous experience. If you have a bottle with a 150mL of head space in Winston- Salem, what volume should it occupy in Boone? The typical pressure in Boone is around 670 torr. Opening shampoo after driving from Winston-Salem (where the typical pressure is around 740torr) to Boone is occasionally a slightly hazardous experience. If you have a bottle with a 150mL of head space in Winston- Salem, what volume should it occupy in Boone?

35. Methanol/air fires can burn at temperatures as high as 1900°C. After shooting an 18.9L methanol rocket down the hall, it is quickly stoppered to seal the remaining gas in the container. What is the pressure inside the container once it cools back down to room temperature (25.0°C)? Assume that atmospheric pressure is 1.00atm. Methanol/air fires can burn at temperatures as high as 1900°C. After shooting an 18.9L methanol rocket down the hall, it is quickly stoppered to seal the remaining gas in the container. What is the pressure inside the container once it cools back down to room temperature (25.0°C)? Assume that atmospheric pressure is 1.00atm. What mass of nitrogen is in a cylinder with a volume of 3.25L and a pressure of 15500 mmHg at 25.0°C? What mass of nitrogen is in a cylinder with a volume of 3.25L and a pressure of 15500 mmHg at 25.0°C? The typical pressure in Boone is around 670 torr. Opening shampoo after driving from Winston-Salem (where the typical pressure is around 740torr) to Boone is occasionally a slightly hazardous experience. If you have a bottle with a 150mL of head space in Winston- Salem, what volume should it occupy in Boone? The typical pressure in Boone is around 670 torr. Opening shampoo after driving from Winston-Salem (where the typical pressure is around 740torr) to Boone is occasionally a slightly hazardous experience. If you have a bottle with a 150mL of head space in Winston- Salem, what volume should it occupy in Boone? A certain car tire has a volume of 29.0L. The maximum rated operating pressure is 80.0psi. The temperature of a hot tire can reach as high as 105°C on a race track. What is the maximum amount of gas that should be pumped into the cold tire to ensure it doesn’t burst in the middle of a race? (1atm = 14.7 lbs/in 2 ) A certain car tire has a volume of 29.0L. The maximum rated operating pressure is 80.0psi. The temperature of a hot tire can reach as high as 105°C on a race track. What is the maximum amount of gas that should be pumped into the cold tire to ensure it doesn’t burst in the middle of a race? (1atm = 14.7 lbs/in 2 )

36. Collecting a Gas Over Water

37. Mixtures of Gasses How do we deal with them? How do we deal with them? The total pressure is the sum of the pressure of each component. The total pressure is the sum of the pressure of each component. Pressures are additive Pressures are additive P total = P 1 + P 2 + P 3 + P 4 + … P total = P 1 + P 2 + P 3 + P 4 + … P 1 = Pressure of Component 1 = Partial Pressure of 1 P 1 = Pressure of Component 1 = Partial Pressure of 1 Dalton’s Law of Partial Pressures Dalton’s Law of Partial Pressures

38. Practice The atmosphere is made up of many gasses. The three largest components are nitrogen, oxygen, and argon gasses with partial pressures of 0.78084atm, 0.20946atm, and 0.00934atm respectively. What is the partial pressure of all of the minor components of air combined? The atmosphere is made up of many gasses. The three largest components are nitrogen, oxygen, and argon gasses with partial pressures of 0.78084atm, 0.20946atm, and 0.00934atm respectively. What is the partial pressure of all of the minor components of air combined?

39. Collecting a Gas Over Water Vapor Pressure of Water – the partial pressure of water in an air sample that is saturated with water vapor. Temperature Dependent

40. Practice How many moles of oxygen gas were produced by the decomposition of potassium chlorate with a manganese(IV) oxide catalyst if 250mL of oxygen was collected over water at 740mmHg and 22.0°C? The vapor pressure of water at 22.0°C is 19.83mmHg. How many moles of oxygen gas were produced by the decomposition of potassium chlorate with a manganese(IV) oxide catalyst if 250mL of oxygen was collected over water at 740mmHg and 22.0°C? The vapor pressure of water at 22.0°C is 19.83mmHg. How many grams of potassium chlorate were decomposed?

41. Kinetic Molecular Theory for Ideal Gasses A rather simple but powerful system A rather simple but powerful system Can derive the ideal gas law from it Can derive the ideal gas law from it Describes gases pretty well under certain conditions Describes gases pretty well under certain conditions Not perfect and has limitations Not perfect and has limitations

42. Kinetic Molecular Theory for Ideal Gases 1. Gases consist of large numbers of particles (atoms or molecules) that are in continuous random motion. 2. The combined volume of all the molecules of the gas is negligible compared to the total volume in which the gas is contained. 3. Attractive and repulsive forces between gas molecules are negligible. 4. Energy is transferred between particles during collisions. These collisions are completely elastic (there is no loss in kinetic energy.) 5. The average kinetic energy of the particles is proportional to the absolute temperature. At a given temperature, all different gases have the same average kinetic energy.