Re: Weight of compressed air.

[Ludwik Kowalski <kowalskiL@MAIL.MONTCLAIR.EDU>]

Mea culpa. In copying the values of a and b from the Tipler's
textbook I did not notice that only "a" was in SI units while "b"
was in cm^3/mole. Perhaps this will be corrected in the next
edition (to minimize a chance of another entrapment).

Paolo Cavallo wrote:

> ----- Original Message -----
> From: "Ludwik Kowalski" <kowalskiL@MAIL.MONTCLAIR.EDU>
> To: <PHYS-L@lists.nau.edu>
> Sent: Friday, March 08, 2002 10:42 AM
> Subject: Re: Weight of compressed air.
>
> > > Quick question for everyone out there.  I am looking for the weight of air
> > > in a container that is pressurized to 80 psi.  The container is a cylinder
> > > that is 1 foot in length and 9 inches in diameter.  I am not concerned about
> > > the weight of the container itself.  How well does Boyle's Law hold for air?
> >
> > The Van der Waals equation constants for nitrogen are a=0.14
> > and b=39.1 of SI units. Compare what that equation gives you
> > with what Boyle's equation gives at different pressures to get
> > the answer...
>
> That's a really nice exercise and I never tried it. I wish to thank you
> for the idea. I had no hint about how near the two result still are
> at such a high pressure.
> Just to have a precise reference, you missed a factor 10^-6 in b.
>
> Best regards,
>
> PC