1 / 127

Larry Emme Chemeketa Community College

Gases Chapter 12. Larry Emme Chemeketa Community College. Properties of Gases. May be compressed Expand to fill container Low density May be mixed Constant, uniform pressure on container walls. The Kinetic- Molecular Theory. The Kinetic-Molecular Theory.

turi
Download Presentation

Larry Emme Chemeketa Community College

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Gases Chapter 12 Larry Emme Chemeketa Community College

  2. Propertiesof Gases

  3. May be compressed • Expand to fill container • Low density • May be mixed • Constant, uniform pressure on container walls

  4. The Kinetic-Molecular Theory

  5. The Kinetic-Molecular Theory • KMT is based on the motions of gas particles. • A gas that behaves exactly as outlined by KMT is known as an ideal gas. • While no ideal gases are found in nature, real gases can approximate ideal gas behavior under certain conditions of temperature and pressure (high temperature & low pressure).

  6. Principle Assumptions of the KMT • Gases consist of tiny subatomic particles. • The distance between particles is large compared with the size of the particles themselves. • Gas particles have no attraction for one another.

  7. Principle Assumptions of the KMT • Gas particles move in straight lines in all directions, colliding frequently with one another and with the walls of the container.

  8. Principle Assumptions of the KMT • No energy is lost by the collision of a gas particle with another gas particle or with the walls of the container. All collisions are perfectly elastic. • The average kinetic energy for particles is the same for all gases at the same temperature, and its value is directly proportional to the Kelvin temperature.

  9. Kinetic Energy

  10. mH = 2 vH 4 2 2 = mO = 32 1 vO 2 2 Kinetic Energy • All gases have the same kinetic energy at the same temperature. • As a result, lighter molecules move faster than heavier molecules.

  11. Parameters forDescribing Gases

  12. Force per unit area mmHg (torr) or atm Pressure P Volume of container Volume liter V No. of moles of gas n No.of moles mole Absolute temp of gas Temperature K T

  13. Measurement of Pressure of Gases

  14. The pressure resulting from the collisions of gas molecules with the walls of the balloon keeps the balloon inflated.

  15. Pressure equals force per unit area.

  16. Evangelista Torricelli 1644

  17. Measuring Pressure Attempts to pump water out of flooded mines often failed because H2O can’t be lifted more than 34 feet.

  18. Measuring Pressure Torricelli believed the reason was that the P of atmosphere could not hold anything heavier than a 34’ column of water.

  19. Measuring Pressure The atmosphere would support a column of H2O > 34 feet high. 1 Atm 34’ column of water

  20. Torricelli Barometer Pressure of the atmosphere supports a column of Hg 760 mm high. 1 atm = 760 mm Hg 760 torr 29.92 in Hg 14.7 lb/in2 101,325 Pa vacuum 1 atm Mercury used because it’s so dense.

  21. Boyle’s Law1662

  22. Robert Boyle

  23. At constant temperature (T), the volume (V) of a fixed mass of gas is inversely proportional to the Pressure (P).

  24. Graph of pressure versus volume. This shows the inverse PV relationship of an ideal gas.

  25. The effect of pressure on the volume of a gas.

  26. P1 = 500 torr V1 = 8.00 L P2 = ? V2 = 3.00 L An 8.00 L sample of N2 is at a pressure of 500. torr. What must be the pressure to change the volume to 3.00 L? (T is constant). Step 1. Organize the given information:

  27. An 8.00 L sample of N2 is at a pressure of 500. torr. What must be the pressure to change the volume to 3.00 L? (T is constant). Step 2. Write and solve the equation for the unknown.

  28. An 8.00 L sample of N2 is at a pressure of 500. torr. What must be the pressure to change the volume to 3.00 L? (T is constant). Step 3. Put the given information into the equation and calculate.

  29. A tank of O2 contains 1500. ml of gas at a pressure of 350. torr. What volume would the gas occupy at 1000. torr? Step 1. Organize the given information: V1 = 1500. ml P2 = 1000. torr P1 = 350. torr V2 = ?

  30. A tank of O2 contains 1500. ml of gas at a pressure of 350. torr. What volume would the gas occupy at 1000. torr? Step 2. Write and solve the equation for the unknown.

  31. A tank of O2 contains 1500. ml of gas at a pressure of 350. torr. What volume would the gas occupy at 1000. torr? Step 3. Put the given information into the equation and calculate. = 525 ml

  32. Charles’ Law1787

  33. Jacques Charles

  34. O2 N2 Volume-temperature relationship of methane (CH4).

  35. Charles’ Law At constant pressure the volume of a fixed mass of gas is directly proportional to the absolute temperature.

  36. Effect of temperature on the volume of a gas. Pressure is constant at 1 atm. When temperature increases at constant pressure, the volume of the gas increases.

  37. V1 = 255 mL T1 = 75oC = 348 K V2 = ? T2 = 250oC = 523 K A 255 mL sample of nitrogen at 75oC is confined at a pressure of 3.0 atmospheres. If the pressure remains constant, what will be the volume of the nitrogen if its temperature is raised to 250oC? Step 1. Organize the information (remember to make units the same):

  38. A 255 mL sample of nitrogen at 75oC is confined at a pressure of 3.0 atmospheres. If the pressure remains constant, what will be the volume of the nitrogen if its temperature is raised to 250oC? Step 2. Write and solve the equation for the unknown:

  39. V1 = 255 mL T1 = 75oC = 348 K V2 = ? T2 = 250oC = 523 K A 255 mL sample of nitrogen at 75oC is confined at a pressure of 3.0 atmospheres. If the pressure remains constant, what will be the volume of the nitrogen if its temperature is raised to 250oC? Step 3. Put the given information into the equation and calculate:

  40. A tank of O2 contains 16.0 L at 500.K is allowed to expand to a volume of 20.0 L. Find the new temperature (constant pressure). Step 1. Organize the given information: V1 = 16.0 L V2 = 20.0 L T1 = 500.K T2 = ?

  41. A tank of O2 contains 16.0 L at 500.K is allowed to expand to a volume of 20.0 L. Find the new temperature (constant pressure). Step 2. Write and solve the equation for the unknown.

  42. A tank of O2 contains 16.0 L at 500.K is allowed to expand to a volume of 20.0 L. Find the new temperature (constant pressure). Step 3. Put the given information into the equation and calculate: = 625 K

  43. Gay-Lussac’s Law1802

  44. Joseph Gay-Lussac

  45. Increased pressure is due to more frequent and more energetic collisions of the gas molecules with the walls of the container at the higher temperature. Lower T Lower P Higher T Higher P The pressure of a gas in a fixed volume increases with increasing temperature.

  46. The pressure of a fixed mass of gas, at constant volume, is directly proportional to the Kelvin temperature.

  47. P1 = 21.5 atm T1 = 40oC = 313 K P2 = ? T2 = 100oC = 373 K At a temperature of 40.oC an oxygen container is at a pressure of 21.5 atmospheres. If the temperature of the container is raised to 100.oC what will be the pressure of the oxygen? Step 1. Organize the information (remember to make units the same):

  48. At a temperature of 40.oC an oxygen container is at a pressure of 21.5 atmospheres. If the temperature of the container is raised to 100.oC what will be the pressure of the oxygen? Step 2. Write and solve the equation for the unknown:

  49. P1 = 21.5 atm T1 = 40oC = 313 K P2 = ? T2 = 100oC = 373 K At a temperature of 40.oC an oxygen container is at a pressure of 21.5 atmospheres. If the temperature of the container is raised to 100.oC what will be the pressure of the oxygen? Step 3. Put the given information into the equation and calculate:

  50. Combined Gas Laws

More Related