Difference between an ideal gas and a real gas

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Discussion Overview

The discussion focuses on the differences between ideal gases and real gases, exploring theoretical concepts and characteristics of each type of gas. Participants provide explanations and clarifications regarding the assumptions and properties associated with ideal and real gases.

Discussion Character

  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants describe an ideal gas as a collection of particles with no intermolecular forces except during contact, likening it to billiard balls that bounce off each other without energy loss.
  • Others note that real gases experience electromagnetic interactions, leading to attractive and repulsive forces that affect their behavior and compactness.
  • One participant adds that ideal gas particles are considered infinitesimally small, while real gas particles have finite sizes.
  • Another participant emphasizes that collisions in an ideal gas are assumed to be elastic and that the time between collisions is much greater than the collision duration.

Areas of Agreement / Disagreement

Participants generally agree on the fundamental differences between ideal and real gases, but there are nuances in the explanations provided, indicating a lack of complete consensus on all aspects of the topic.

Contextual Notes

Some assumptions regarding the behavior of gases and the conditions under which ideal gas laws apply may not be fully explored, and the discussion does not resolve the complexities of real gas behavior under various conditions.

pavadrin
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Hey
Could somebody please explain what the difference between an ideal gas and a real gas are? Or post a suitable link from which I can understand the concept surrounding this issue.
Thanks
Pavadrin
 
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An ideal gas is a picture of a gas where there are no forces in between molecules except when they are in contact. You can think of an ideal gas as a collection of billiard balls bouncing around in 3 dimensions. To the billiard balls there is no difference in being a 1 meter away from the next closest ball, or being 1 mm away. Because there are no forces between the different balls. When they hit they bounce off each other instantly with no loss of energy and go in new directions.

In a real gas, there are additional forces in play due to electromagnetic interactions betweeen the molecules. Usually attractive forces are stronger at longer distances and repulsive forces are stronger at very short distances. So real gasses usually will be a little more compact (but not always) because they molecules are pulling each other together. If a gas has strong enough attractive forces, it turns into a liquid, where all the particles will condence so much that they are not allowed to go free of each other anymore.

The only difference between an ideal gas and a real gas is the types of forces we are allowed to use. There is no such thing as an ideal gas in real life, but it is a very good approximation for many gasses like N2, O2, and Nobel gases. It makes the math a lot easier to work with.

~Lyuokdea
 
Lyuokdea is almost right - but there is one more important difference. Particles of ideal gas are infinitesimally small, while these of real gases have finite sizes.
 
I would just like to add that in an ideal gas, any collisions between the molecules or the container is assumed to be elastic. Also, the collision time is infintesimal when compared with the time between collisions.

~H
 
Last edited:
Thanks you so much for everyone that took the time to kindly reply, especially ~Lyuokdea for the in depth explanation.
Pavadrin
 

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