Gas Laws

• Chemistry


  A branch of natural science that deals principally with the properties of substances, the changes they undergo, and the natural laws that describe these changes
• Kinetic Molecular Theory


  • Gas molecules behave according to varying degrees of pressure, temperature, and volume
  • Gas molecules collide constantly with any matter they encounter
• Rudolf Clausius, James Clerk Maxwell, and Ludwig Boltzmann conducted research and experiments that related the motion of gases with the concepts of heat and kinetic energy


  Middle of the 1800's
• Five postulates of the Kinetic Molecular Theory

  • Gas particles move continuously in random, linear motion and collide with each other or with the container's walls
  • The collision of gas particles is elastic
  • The average kinetic energy of gas particles is directly proportional to their absolute temperature (Kelvin)
  • The intermolecular forces among gas particles are negligible
  • The volume of gas particles is negligible relative to the volume of their container

  
• Kinetic Molecular Theory


  Identification and understanding of the properties of gases
• Pressure (P)


  Force exerted over a given area, P = F/A
• Temperature (T)


  Measurement of the kinetic energy of the gas particles, standard unit is Kelvin (K)
• Volume (V) and amount of Gas in Moles (n)

  Amount of space occupied by the gas particles, depends on the container's volume
• Boyle's Law


  Pressure is inversely proportional to the volume of gas at a constant temperature
• Boyle's Law


  • Example 1: Pressure increases from 1.00 atm to 2.00 atm as volume decreases from 6.0 L to 3.0 L

  Example 2: Initial pressure is 15 atm as volume increases from 30 L to 75 L and final pressure is 6 atm

  Example 3: Balloons shrink as pressure decreases from 1.30 atm to 1.15 atm and volume decreases from 2.35 L to 2.66 L
• Charles' Law


  Volume is directly proportional to absolute temperature at constant pressure
• Avogadro's Law


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• Ideal Gas Law


  PV = nRT
• Boyle's Law: Volume is inversely proportional to pressure at constant temperature and amount of gas
• Charles' Law: Volume is directly proportional to absolute temperature at constant pressure and amount of gas
• Gay-Lussac's Law: Pressure is directly proportional to absolute temperature at constant volume and amount of gas
• Avogadro's Law: Volume is directly proportional to the amount of gas at constant pressure and temperature
• Combined Gas Law: The product of pressure, volume, and temperature is constant for a fixed amount of gas
• Ideal Gas Law: Pressure, volume, temperature, and amount of gas are related by the equation PV = nRT
• Boyle's Law


  Relationship of the volume and pressure of gas
• Robert Boyle


  1627-1691
• Robert Boyle was an Angio-Irish chemist
• Robert Boyle and Robert Hooke had been experimenting on the relationship of the volume and pressure of gas using air trapped by mercury in the sealed end of a J-shaped tube