Molecular Dynamics Simulation

Pressure-Volume Relation


How does the pressure of a gas depend upon the volume of the gas?

For a fixed amount of gas at a constant temperature, Boyle's Law states that the quantity P V is a constant. (P is the pressure and V is the volume.) Does the Kinetic Molecular Theory correctly predict this behavior? If so, why does a decrease in system volume produce an increase in pressure?

Shown below are two molecular dynamics simulations. Both systems are at the same temperature and contain the same number and type of particles. System 1, however, is exactly twice the volume of System 2. Start the simulations and carefully observe the behavior of the particles.

Things to remembers:


  1. Boyle's Law predicts that the pressure of System 2 should be twice the pressure of System 1. Compare the pressures for the two systems. Does Boyle's Law correctly predict the relative pressures?
  2. In terms of the behavior of the particles in the simulations, why is the pressure of System 2 larger than the pressure of System 1?
  3. Boyle's Law predicts that the pressure System 2 should be exactly twice that of System 1. Is this the case? Boyle's Law applies to an Ideal Gas. Why do these gases display a slight degree of non-ideal behavior?
System 1
System 2

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© 2001, 2014, 2023 David N. Blauch