Burns FUNDAMENTALS OF CHEMISTRY

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Burns FUNDAMENTALS OF CHEMISTRY

• Kinetic Theory of Gases

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The Atmosphere

• The atmosphere is the thin layer of gases that
  surround the earth.
• Air is composed of a mixture of gases
• 78 Nitrogen, N2
• 21 Oxygen, O2
• 1 Argon, Ar
• 365 ppm carbon dioxide, CO2
• 0-4 water, H2O

Dry Air
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Physical Properties of Gases

• No definite shape of volume
• expand to fill container, take shape of
  container.
• Compressible
• increase pressure, decrease volume.
• Low Density
• air at room temperature and pressure 0.00117
  g/cm3.
• Exert uniform pressure on walls of container.
• Mix spontaneously and completely.
• diffusion

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Kinetic Theory of Gases

• 1. Gases move continuously, rapidly, randomly in
  straight lines and in all directions.
• 2. Gas particles are extremely tiny and
  distances between them are great.
• 3. Gravitational forces between molecules are
  negligible.
• 4. Collisions between gas molecules are elastic
  (no loss of energy in collision).

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Kinetic Energy

• 5. The average kinetic energy of the gas
  particles (molecules or atoms) is the same for
  all gases at the same temperature.
• Kinetic Energy, K. E., is proportional to the
  Kelvin temperature.
• K. E. ½mv2
• m mass of the gas particle
• v velocity of particle
• When temperature increases velocity of particles
  increases.
• At a fixed temperature, lighter particles move
  faster.

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Pressure

• Pressure is the force exerted per unit area
• Pressure Force/Area
• Atmospheric Pressure is the force per unit area
  exerted by the earths atmosphere.
• Atmospheric Pressure is measured with a
  barometer.
• Pressure can be measured by the height of a
  column of mercury that can be supported by a gas.

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Pressure Units

• mm of mercury (mm Hg)
• 1 mm Hg 1 torr
• 760 mm Hg 1 atm
• 1 atm is 1 atmosphere of pressure, sometimes
  called standard pressure.
• 1 Pascal, Pa, is the SI unit of pressure
• 1 Pa 1 N/m2 9.9 x 10-6 atm