Gases

• Particles in an ideal gas/Kinetic Molecular Theory

  • Have no volume
  • Have elastic collisions
  • Are in constant, random, straight-line motion
  • Don't attract or repel each other
  • Have an avg. KE directly related to Kelvin temperature
• Particles in a REAL gas

  • Have their own volume
  • Attract each other
• Gas behavior is most ideal

  • At low pressures
  • At high temperatures
  • In nonpolar atoms/molecules
• Gases


  • Expand to fill any container
  • Are fluids (like liquids)
  • Have very low densities
• Gases


  • Can be compressed
  • Undergo diffusion & effusion
• Temperature


  Always use absolute temperature (Kelvin) when working with gases
• Barometer


  Measures atmospheric pressure
• Key units of pressure at sea level

  • 101.325 kPa (kilopascal)
  • 1 atm
  • 760 mm Hg
  • 760 torr
  • 14.7 psi
• STP


  Standard Temperature & Pressure: 0°C, 273 K, 1 atm, 101.325 kPa
• Boyle's Law


  The pressure and volume of a gas are inversely related at constant mass & temp
• Charles' Law


  The volume and absolute temperature (K) of a gas are directly related at constant mass & pressure
• Gay-Lussac's Law


  The pressure and absolute temperature (K) of a gas are directly related at constant mass & volume
• Solving gas law problems

  1. Given information

  2. Work
• Avogadro's Principle


  Equal volumes of gases contain equal numbers of moles at constant temp & pressure
• Universal Gas Constant


  R = 0.0821 L·atm/mol·K or R = 8.315 dm3·kPa/mol·K
• Solving Ideal Gas Law problems


  1. Given information

  2. Work