Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Why does pressure due to van der Waals' forces increase as the square of density?

  1. Aug 14, 2011 #1
    In van der Waals' equation for real gases, the adaptation to account for intermolecular attractions in real gas is [itex]a\frac{n^2}{V^2}[/itex]. This implies that the pressure due to the VDW forces on the container is proportional to the square of the density, [itex]\rho^2 = \frac{n^2}{V^2}[/itex].

    When I do calculations following from [itex]P_{VDW}=\frac{\pi \rho^2 \lambda}{H^3}[/itex], I end up with a cubic dependence.

    Is there a qualitative way to imagine why the pressure is proportional to the square of the molecular density, [itex]\rho[/itex]?
     
  2. jcsd
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted



Similar Discussions: Why does pressure due to van der Waals' forces increase as the square of density?
Loading...