- #1
- 1,440
- 7
That came out in my qualifying exam.
The question was if a gas with rotational and vibrational energies enhanced, does obey the Ideal Gas Equation PV=NKT.
You can answer with all the tools you have at hand. My comitee member didn't agree with me, but anyway I persisted in my answer and I said: yes it does, assuming the energetics of the rotation and vibration are uncoupled.
I based my answer on the fact that the only partition function which depends on volume is the Translational partition function. And as we know the pressure can be found as:
[tex]P=NKT\frac{\partial (ln Q)}{\partial V}[/tex]
if you substitute there the partition function, the only contribution comes from the translation one, so the only thing that is producing pressure is the translational motion of the molecules of the gas, no matter if they are vibrating or rotating.
What is your opinion?
PS: God knows that I will remember my persistance in the exam about this fact the rest of my life. I kinda challenged a faculty. But I justified my answer adecuately I think.
The question was if a gas with rotational and vibrational energies enhanced, does obey the Ideal Gas Equation PV=NKT.
You can answer with all the tools you have at hand. My comitee member didn't agree with me, but anyway I persisted in my answer and I said: yes it does, assuming the energetics of the rotation and vibration are uncoupled.
I based my answer on the fact that the only partition function which depends on volume is the Translational partition function. And as we know the pressure can be found as:
[tex]P=NKT\frac{\partial (ln Q)}{\partial V}[/tex]
if you substitute there the partition function, the only contribution comes from the translation one, so the only thing that is producing pressure is the translational motion of the molecules of the gas, no matter if they are vibrating or rotating.
What is your opinion?
PS: God knows that I will remember my persistance in the exam about this fact the rest of my life. I kinda challenged a faculty. But I justified my answer adecuately I think.
Last edited: