Question

Can anyone tell me which are the deviations of real gasses from ideal gasses?

Answer 1

One major difference is that ideal gas molecules don't have potential energy in between them while real gas molecules have.

Answer 2

does (and how) potential energy depend on distance between molecules?

Answer 3

Yes. Most of the potential energy of real gas molecules is Coulomb interaction, while in ideal gas, assumptions are made such that the interaction is negligible.

Answer 4

thanks!
Could you just check if this is good answer on my first question:

Postulates for ideal gasses are:
1. A gas consists of a collection of small particles traveling in straight-line motion and obeying Newton's Laws.
2. The molecules in a gas occupy no volume (that is, they are points).
3. Collisions between molecules are perfectly elastic (that is, no energy is gained or lost during the collision).
4. There are no attractive or repulsive forces between the molecules.

States of ideal gas are described by Boyle's, Charles's, and Gay-Lussac's laws and equation pV=nRT. Ideal gas does not exist.

Molecules of real gases have a volume which can't be neglected, there are intermolecular forces that can't be neglected. State of real gas is described by Wan der Waals equation.

Deviations of real gas from ideal gas are noticeable on high pressures and low temperatures.
When pressure is getting lower, distance between molecules is getting higher and dimensions of molecules could be neglected.
When temperature is getting higher, heat energy of molecules is getting higher and molecular interaction could be neglected.

Answer 5

I would have the following amendments:
1. A classical gas consists of perfectly spherical particles travel in straight line and obeys the conservation of momentum.
2. All molecules are identical.
3. The volume of the molecules is negligible in comparison to the volume of the container.
4. Collisions between molecules and collisions of molecules upon the wall of the container are elastic.
5. Interactions with the exception of collision are absent, including Coulomb and gravitational interaction.
6. Time of collision is negligible in comparison to the time interval between successive collisions.

State of real gas is approximated by VdW equation.

Real gas behaves similarly to ideal gas in low pressure and high temperature.

Answer 6

thank you very much :)

Answer 7

You're welcome