Kinetic theory and Properties of Matter

• Simple model for understanding the behavior of gas

  • Gas is a collection of particles in constant straight line motion
  • Gas particles do not attract or repel each other
  • Gas particles have very small size compared to the space between them
• Kinetic molecular theory of gases


  Assumptions about the behavior of gas particles
• Kinetic energy of gas particles is proportional to temperature in Kelvin scale
• Physical properties of gases

  • Highly compressible
  • Exert pressure equally in all directions
  • Have low density than solid and liquid
  • Volume and shape not fixed, take the volume and shape of the container
  • Mix evenly and completely
• Gas laws


  Mathematical equations that describe the relationships between volume, temperature, pressure and quantity of gas
• The volume of one mole of any substance at standard temperature and pressure (STP) is 22.4 litres
• Molar volumes


  • 1 mole of carbon dioxide
  • 1 mole of oxygen
  • 1 mole of methane
• The volume of 2 moles of carbon dioxide at STP is 44.8 litres
• The volume of 89.6 litres of carbon dioxide at STP is 4 moles