April 27, 2024, 08:59:09 PM
Forum Rules: Read This Before Posting


Topic: Using Z=PV/RT  (Read 4271 times)

0 Members and 1 Guest are viewing this topic.

Offline clemson junior

  • Very New Member
  • *
  • Posts: 1
  • Mole Snacks: +0/-0
Using Z=PV/RT
« on: September 08, 2010, 02:37:12 PM »
Use Z=PV/RT to demonstrate that for any gas Tα=1+T(∂lnZ/∂T) {constant P} and Pκ=1-P(∂lnZ/∂P){constant T}?

in an earlier questoin we found that:
alpha(α) = (1/V)(∂V/∂T){constant P}
= (1/T)

and kappa(κ)=(-1/V)(∂V/∂P){constant T}
= [1/(1+ωP)][1/P]

These were derived from PV=RT(1+ωP) where ω is some temperature-independent constant.

"Remark: Using experimental data for alpha and kappa the above formulas allow to restore the equation of state by integration over T and P. Once the equation of state is determined all thermodynamic potentials can be obtained as we shall learn later on." (don't know if this pertains to the solution or not it was at the bottom of the problem.)

Offline MrTeo

  • Chemist
  • Full Member
  • *
  • Posts: 312
  • Mole Snacks: +31/-9
  • Gender: Male
Re: Using Z=PV/RT
« Reply #1 on: September 09, 2010, 11:48:52 AM »
Just to tidy up your request  ;)

Given that:

$$ Z=\frac{pV}{RT} \\
PV=RT\left(1+\omega T\right) \\
\alpha=\frac{1}{V}\cdot\left(\frac{\partial V}{\partial T}\right)_p=\frac{1}{T} \\
\kappa=-\frac{1}{V}\cdot\left(\frac{\partial V}{\partial p}\right)_T=\frac{1}{p\left(1+\omega p\right)} /$$

demonstrate that:

$$ T_{\alpha}=1+T\cdot\left(\frac{\partial \ln Z}{\partial T}\right)_p \\
p_{\kappa}=1-p\cdot\left(\frac{\partial \ln Z}{\partial p}\right)_T /$$

What approach have you tried? Seems like you only have to solve the derivatives (though I haven't worked on it yet...)
The way of the superior man may be compared to what takes place in traveling, when to go to a distance we must first traverse the space that is near, and in ascending a height, when we must begin from the lower ground. (Confucius)

Sponsored Links