Category Archives: Thermal Physics
Ideal Gas
An ideal gas is a theoretical gas composed of a set of randomly-moving, non-interacting point particles. The ideal gas concept is useful because it obeys the ideal gas law, a simplified equation of state:
where 
is the pressure of the gas, 
is its volume, 
is the amount of substance (in moles), 
is the Gas Constant 
and 
is the absolute temperature.
At normal conditions such as standard temperature and pressure, most real gases behave qualitatively like an ideal gas. Generally, a gas behaves even more like an ideal gas at higher temperature and lower density (i.e. lower pressure), as the work performed by intermolecular forces (i.e. potential energy) becomes less significant compared with the particles' kinetic energy, and the size of the molecules becomes less significant compared to the empty space between them.
For a monoatomic ideal gas, internal energy 
is simply the sum of the random kinetic energies of the constituent molecules and 
.
