Ideal Gas Law: Encyclopaedic Experimental Data

[Prokop]

The “ideal gas” law

The well-known, encyclopaedic experimental data (about gas compressability factor) show the general trend:
the more rarefied gas the more accurate “ideal gas” law,
or the same in other terms:
the higher vacuum the more accurate “ideal gas” law.
1) Are another experimental data which contradict the trend ?
2) Are the theory which explains the trend ? (Classic or quantum molecular-kinetic theories do not considered as absolutely unsuitable).
3) Does your conclude the so called “ideal gas” is namely vacuum ?

 

[Nick89]

I'm not sure if I understand your questions correctly, but I'll have a go at answering them:

1) I don't know but I don't think so.

2) The ideal gas law is a law derived from statistical mechanics. It treats the gas molecules as point particles, with no volume. It also assumes the particles do not 'feel' each other in any way except that they bounce elastically with each other and the walls.

Now imagine if you have a LOT of particles, they will take up a lot of space. But in the ideal gas law model, they won't take up any space at all since they are all point particles! Clearly the law will not work very well there.
If you have very little particles however, the little volume they take up will not be so important and the ideal gas law will work much better.

3) An ideal gas is not a vacuum, since a (perfect) vacuum means actually no gas at all (this cannot exist in reality). An ideal gas does not exist, it is merely a theoretical model of a gas.

 

[baba89]

Thank you for sharing this interesting topic on the ideal gas law and its relationship with experimental data.

1) To answer your first question, yes, there are experimental data that contradict the trend of the ideal gas law becoming more accurate with higher vacuum. One example is the behavior of real gases at high pressures, where deviations from the ideal gas law become more significant. Another example is the behavior of gases at extremely low temperatures, where quantum effects become more prominent and the ideal gas law is no longer accurate.

2) As for the theory that explains this trend, both classical and quantum molecular-kinetic theories can provide insights into the behavior of gases at different conditions. For example, classical kinetic theory can explain the trend observed in the experimental data, as it considers gas particles as point masses with no volume and assumes that intermolecular forces are negligible. On the other hand, quantum molecular-kinetic theories take into account the size and interactions of gas particles and can better explain the behavior of gases at extreme conditions.

3) Based on the experimental data and theories, it would not be accurate to conclude that the "ideal gas" is solely vacuum. The ideal gas law is a simplified model that assumes ideal conditions, and while it can accurately describe the behavior of gases under certain conditions, it does not fully capture the complexities of real gases. The term "ideal gas" is used to refer to the idealized behavior of gases in these conditions, but it does not mean that the gas is literally a vacuum.