- Joined
- Apr 16, 2010
- Messages
- 660
- Reaction score
- 3
This is a concept that his been troubling me for the past hour.
EK, Kaplan, and most websites all seem to agree that for Real Gases:
1. Preal < Pideal - because molecules DO have attractive forces
2. Vreal > Videal - because molecules DO have volume
It's this second statement that's troubling me, and one that I can't seem to fully understand. There logic is something like this:
Videal = Vempty
Vreal = Vparticles + Vempty = Vparticles + Videal
Vreal > Videal
Website: http://www.mpcfaculty.net/mark_bishop/real_gases.htm
TBR and TPR on the other hand states the exact opposite:
Here's a statement taken from The Princeton Review:
In my opinion TBR & TPR's logic makes sense to me. How exactly can the ideal volume be GREATER for a real gas. If we assumed the volume for an ideal gas was the volume of it's container... you can't have "GREATER" volume. It just didn't make sense.
Anyways, who the heck is right? Normally I'd be like whatever and move on. But I find myself stuck in a position where I either get multiple choice questions WRONG for EK and Kaplan (if I used TBR and TPR's logic) or multiple choice questions WRONG for TPR and TPR (if I use EK and Kaplans logic).
EK, Kaplan, and most websites all seem to agree that for Real Gases:
1. Preal < Pideal - because molecules DO have attractive forces
2. Vreal > Videal - because molecules DO have volume
It's this second statement that's troubling me, and one that I can't seem to fully understand. There logic is something like this:
Videal = Vempty
Vreal = Vparticles + Vempty = Vparticles + Videal
Vreal > Videal
Website: http://www.mpcfaculty.net/mark_bishop/real_gases.htm
Crayton from EK
The fact that Vreal > Videal is just that the real volume of the gas must also include the amount of volume that the actual gas molecules take up themselves (the size of the atoms or molecules, which is dictated by the size of their electron clouds).
TBR and TPR on the other hand states the exact opposite:
Pg. 10, Chapter 6 Gen Chem
Here's a quote taken from TBR Gen Chem:
Because they have volume (molecules) on the microscopic level, the actual free space (space not occupied by molecules) is less than the volume of the container. The bigger the molecules, the greater the volume they occupy, thus the greater the deviation. The more molecules, the greater the volume they occupy, thus the greater the deviation. The free space (ideal volume) is found by taking the container volume and subtracting the volume of the molecules. This means that the ideal volume (volume of the empty space) is equal to the difference between the volume of the container and the volume of the particles.
Therefore: Videal = Vcontainer - Vparticles
Here's a statement taken from The Princeton Review:
TPR - Pg. 524, Physics
And Vreal < Videal because moles of real gas do have volume that reduces the effective volume of the container (since the moles take up space, there is less space in the container for all the other particles to occupy.)
In my opinion TBR & TPR's logic makes sense to me. How exactly can the ideal volume be GREATER for a real gas. If we assumed the volume for an ideal gas was the volume of it's container... you can't have "GREATER" volume. It just didn't make sense.
Anyways, who the heck is right? Normally I'd be like whatever and move on. But I find myself stuck in a position where I either get multiple choice questions WRONG for EK and Kaplan (if I used TBR and TPR's logic) or multiple choice questions WRONG for TPR and TPR (if I use EK and Kaplans logic).