Behavior of Gases

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Behavior of Gases
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• Gas particles are in constant motion
• Collisions of these particles in the air causes
  pressure
• Pressure force per unit of area or P F/A

3

• The more gas particles in a container the more
  they collide with the walls of the container and
  the greater the pressure

4

• Pressure is measured in a unit called a Pascal
  (Pa)
• P F/A F measured in Newtons (N) and A
  measured in m2
• Pascal N/m2
• Since 1 N/m2 is such a small unit we typically
  record pressure in kPa or kilopascals

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Boyles Law

• If you increase the volume of a container of gas,
  and hold the Temp constant, Pressure will be
  decreased
• Volume
• Pressure
• If you decrease the volume of the container and
  hold the temperature constant, Pressure will
  increase
• Volume
• Pressure

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Boyles Law in Action

• Since pressure and volume are INDIRECTLY related
  the following equation can be formed
• P1V1 P2V2
• Using this equation you can find missing values
• Assumes constant temperature

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Example of Boyles Law

• If a balloon has a volume of 10 L at a pressure
  of 101k Pa. What will be the new volume when the
  pressure drops to 43.0 kPa?

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Pressure/ Temp Relationship

• If you heat gas particles they move faster
• The faster they move the more they strike the
  sides of their container
• If the container is a FIXED volume (cant
  expand), the pressure will increase as the Temp
  increases
• Temp
• Pressure
• Constant Volume

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• If Temperature is increased then one of the other
  factors must also increase due to faster moving
  particles
• With a fixed volume then the pressure will
  increase
• With a fixed pressure then the volume will
  Increase (balloons)

10
Charles Law

• In some cases where the container can expand, the
  volume increases not the pressure
• Volume of gas increases as temp increases as long
  as pressure does NOT change
• Volume
• Temperature
• The reverse is also true volume decreases as
  temperature decreases

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CharlesLaw

• The following equation depicts Charles Law
• V1/ T1 V2/ T2
• Temp is in Kelvin
• Pressure is constant

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Example of Charles Law

• What would be the resulting volume if a 2.0 L
  balloon at 25 C that was placed in a container
  of ice water at 3C?
• To convert celsius to Kelvin simple add 273 and
  drop the degrees symbol