Property of Gases

1
Property of Gases

• Gas Laws

2
Properties of Gases

• Gases Have Low Density
• Gases Are Highly compressible
• Gases are considered Fluids

3
Gases as Fluids

• The word fluid means any substance that can
  flow.
• Gas particles can flow because they are
  relatively far apart and therefore are able to
  move past each other easily.

4
Atmospheric Pressure

• Air Pressure
• The forces of gas molecules as they collide with
  each other and with the surface of Earth.
• The density of the air changes when you change
  altitudes.
• The higher you are the less the pressure less air
  pushing down
• The closer you are to sea level the higher the
  pressure more air pushing down

5
Measuring Pressure/Force

• pressure
• Force divided by area
• Pressure may also be defined as the amount of
  force exerted per unit area of surface.
• The unit of force in SI units is the Newton (N).
• One newton is the force that gives an
  acceleration of 1 m/s2 to an object whose mass is
  1 kg.
• 1 newton 1 kg X 1 m/s2 1 N

6
Measuring Pressure/Force

• The SI unit of pressure is the
• Pascal , Pa
• The force of one newton applied over an area of
  one square meter
• 1 Pa 1 N/1 m2

7
Measuring Pressure

• Atmospheric pressure can be measured by a
  barometer.
• The atmosphere exerts pressure on the surface of
  mercury in the dish.
• This pressure goes through the fluid and up the
  column of mercury.
• The mercury settles at a point where the pressure
  exerted downward by its weight equals the
  pressure exerted by the atmosphere.

8
Mercury Barometer

9
Pressure Units

• 1 atmosphere, 1 ATM
• 760 mm (millimeters of mercury)
• One millimeter of mercury is also called a torr
• Standard temperature and pressure
• STP
• 0 C and 1 ATM

10
Pressure Units
11
Kinetic Molecular Theory

• gas particles are in constant rapid, random
  motion.
• The particles of a gas are very far apart
  relative to their size.
• This idea explains the fluidity and
  compressibility of gases