Chem

• Kinetic Molecular Theory


  A theory that describes the behavior of matter in terms of particles in motion
• Properties of the Kinetic Molecular Theory


  • Volume
  • Attraction/Repulsion
  • Motion
  • Collision
  • Temperature
• Volume


  • The volume occupied by the molecules of the gas is negligible compared to the volume of the gas itself
• Attraction/Repulsion


  • The molecules of an ideal gas exert no attractive forces on each other, or on the walls of the container
• Motion


  • The molecules are in constant random motion
• Collision


  • Collisions are perfectly elastic; when two molecules collide, they change their directions
• Temperature


  • The average kinetic energy of the gas molecules is directly proportional to the absolute temperature
• Particle Size


  • Small particles, separated by huge amounts of empty space
  • Experience no significant amount of attractive/repulsive forces
  • Gases have very low density
• Particle Motion


  • Constant, random motion
  • Move in a straight line, until collision
  • Collisions are elastic (no loss of kinetic energy)
• Particle Energy


  • Kinetic Energy (KE) = ½ mv2 , where m = mass, v = velocity
  • Mass and velocity determine the KE
  • All particles don't have the same KE
  • Temperature: Measure of average kinetic energy
• Which part of the atmosphere exhibits high air pressure?

  Low air pressure?
• Pressure decreases as altitude increases
• Barometers and manometers are used to measure pressure
• Units of Pressure, Temperature and Volume

  • Pressure: atm, Torr, Pa, mmHg
  • Temperature: K
  • Volume: L
• Standard Temperature & Pressure = 273.15 K, 1 atm
• Gas Laws:

  Boyle's Law

  Charles' Law

  Gay-Lussac's Law
• Boyle's Law states that pressure and volume are inversely proportional The standard equation is:

  P1V1 = P2V2
• Charles' Law states that volume and temperature are directly proportional. The standard equation is:

  V1/T1 = V2/T2
• Gay Lussac's Law states that it is directly proportional; to absolute temperature at constant pressure. The standard equation is:

  P1/T1 = P2/T2
• In Boyle's Law:

  V2 = P1V1/P2

  P2 = P1V1/V2

  V1 = P2V2/P1

  P1 = P2V2/V1
• In Charles' Law:

  V2 = T2V1/T1

  T2 = T1V2/V1
• In Gay Lussac's Law

  T2 = T1P2/P1

  P2 = T2P1/T1