In: Chemistry
Contrast ideal vs. nonideal/real gases, and explain why very high pressure and very low temperature gases behave nonideally. (6 points)
Ideal Gas | NonIdeal gas |
There is no attractive or repulsive force between gas molecules. | There is a little attractive or repulsive force between gas molecules. |
It was assumed that ideal gas molecules do not occupy any volume. | Nonideal gas molecules occupy small volume |
The collisions between ideal gas molecules are elastic collision. | The collisions between ideal gas molecules are inelastic collisions. |
Ideal gas follow PV=nRT formula |
Nonideal gas follow the van-der-Walls formula, (p+an2/V2) (V-nb) = nRT |
At higher temperature molecular kinetic energy increases enough so the molecules can overcome the effect of intermolecular attraction or repulsion. So the term an2/V2 which arises due to intermolecular attraction of molecules can be neglected.
The 2nd term nb arise as the nonideal gas occupy a finite volume. At low pressure, the volume of gas increase so much that the effect of the finite volume was reduced.
So the van-der-Walls equation becomes PV=nRT i.e gas law of ideal gas. So at high temperature and low-pressure non-ideal gas behave ideally.