Panel 3: Physical Characteristics of Gases

The physical characteristics of a sample of gas are the following:

  1. volume of the container, typically measured in liters.
  2. pressure which describes the force exerted against the walls of the container because of molecules colliding with them. The pressure is typically measured in atmospheres.
  3. temperature of the gas, which is proportional to the average kinetic energy of the moving molecules. The temperature is always measured in Kelvins. (It is very important in working gas problems to make sure that you have the temperature correctly converted to Kelvins!)
  4. number of moles of gas molocules.
Gases have the interesting property that the physical behavior of one gas is pretty much identical to the behavior of any other gas. (The chemical behavior, describing possible reactions, is not the same, though!) The remainder of this tutorial describes the relations between the four quantities, volume, pressure, temperature and the number of moles.