1 / 14

The Nature of Gases – Part 2

Gas Pressure. The Nature of Gases – Part 2. Objectives. When you complete this presentation, you will be able to: describe gas pressure in terms of the motion of gas particles. describe the invention of the barometer. describe the derivation of the units of pressure.

jill
Télécharger la présentation

The Nature of Gases – Part 2

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. Gas Pressure The Nature of Gases – Part 2

  2. Objectives • When you complete this presentation, you will be able to: • describe gas pressure in terms of the motion of gas particles. • describe the invention of the barometer. • describe the derivation of the units of pressure. • convert between the units of pressure.

  3. Introduction • Gas pressure is the result of the force of gas molecules exerted on a surface. • The force of a single molecule of gas in insignificant, but the force of trillions of molecules becomes measurable. • A vacuumis a volume where there are no gas molecules bouncing off a surface. • Atmospheric pressure results from the collision of air molecules with objects.

  4. Measuring Pressure • We measure the pressure of a gas by using an instrument called a barometer. • The barometer was invented in 1643by the Italian physicist Evangelista Torricelli. • He made a barometer from a tube of glass (sealed at one end) and a trough of mercury.

  5. Measuring Pressure • We measure the pressure of a gas by using an instrument called a barometer. • The barometer was invented in 1643by the Italian physicist Evangelista Torricelli. • He made a barometer from a tube of glass (sealed at one end) and a trough of mercury.

  6. Measuring Pressure • We measure the pressure of a gas by using an instrument called a barometer. • The barometer was invented in 1643by the Italian physicist Evangelista Torricelli. • He made a barometer from a tube of glass (sealed at one end) and a trough of mercury. • The airpressure on the Hg held the column up.

  7. Pressure Units • The air pressure in a barometer is measured by measuring the heightof the mercury column. • Under standard conditions, a column of mercury will be 760 mmin height. • So, we say that 1 atmosphere of pressure (1 atm) is equal to 760 mm Hg.

  8. Pressure Units • Another unit for pressure uses SI units for force (newtons, N) per area (m2) which is called a Pascal, (Pa). • Under standard conditions, 1 atm of pressure is equal to 101,300 Pa = 101.3 kPa.

  9. Pressure Units • Our conversions are: 1.000atm = 760.0 mm Hg = 101.3 kPa

  10. Let’s do some examples

  11. Example 1 A container of oxygen gas has a pressure of 0.450 atm. Find the pressure in mm Hg and kPa. Conversions: 1.000 atm = 760.0 mm Hg = 101.3 kPa Solution: 0.450 atm 760.0 mm Hg 101.3 kPa 342 mm Hg = = = 1.000 atm 1.000 atm 1 1 0.450 atm 45.6 kPa =

  12. Example 2 A container of nitrogen gas has a pressure of 855 mm Hg. Find the pressure in atm and kPa. Conversions: 1.000 atm = 760.0 mm Hg = 101.3 kPa Solution: 855 mm Hg 1.000 atm 101.3 kPa 1.13 atm = = = 760.0 mm Hg 760.0 mm Hg 1 1 855 mm Hg 114 kPa =

  13. Example 3 A container of hydrogen gas has a pressure of 97.3 kPa. Find the pressure in atm and mm Hg. Conversions: 1.000 atm = 760.0 mm Hg = 101.3 kPa Solution: 97.3 kPa 1.000 atm 760.0 mm Hg 0.961 atm = = = 1 1 101.3 kPa 101.3 kPa 97.3 kPa 730 mm Hg =

  14. Summary • Gas pressure is the result of the force of gas molecules exerted on a surface. • Atmospheric pressure results from the collision of air molecules with objects. • We measure the pressure of a gas by using an instrument called a barometer invented in 1643 by the Italian physicist Evangelista Torricelli. • Our conversions are: 1.000 atm = 760.0 mmHg = 101.3 kPa

More Related