Solving the Mystery of Ideal Gases

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Discussion Overview

The discussion revolves around the properties of ideal gases, specifically focusing on statements regarding their behavior and characteristics. Participants are examining which statements about ideal gases are correct or incorrect, with a particular emphasis on intermolecular forces and the implications of these forces on gas behavior.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • One participant asserts that statement D, which claims there are intermolecular forces between molecules, is incorrect for ideal gases.
  • Another participant questions the reasoning behind the assertion that ideal gases have no intermolecular forces, pointing out that if there were truly no forces, compressing an ideal gas would require no work.
  • A different participant highlights a contradiction in the understanding of ideal gases, noting that while they are said to undergo elastic collisions, this implies the presence of forces during collisions.
  • Some participants reference competitive exam materials to support the claim that real gases do not exhibit intermolecular forces, while others counter that real gases do have such forces.
  • One participant clarifies that while the force of repulsion is not linear with distance, it does not imply the absence of force altogether.

Areas of Agreement / Disagreement

Participants express differing views on the presence of intermolecular forces in ideal gases, with no consensus reached on which statements are definitively correct or incorrect. The discussion remains unresolved regarding the implications of these forces on the behavior of gases.

Contextual Notes

There are unresolved assumptions regarding the definitions of ideal and real gases, as well as the implications of intermolecular forces on gas behavior. The discussion reflects varying interpretations of these concepts.

siewwen168
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hello,i have question to ask here. :smile:

1. which of the following is not correct for
an ideal gas?
A. the average kinetic energy of the gas
increases with temperature
B. the force of repulsion between
molecules is proportional to the
distance between them
C. the gas molecules have mass but
negligible volume.
D. there are intermolecular forces
between molecules

my answer is D,but the answer given is B,why? :confused:
 
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because i thought D is the wrong answer,ideal gas don't have intermolecular forces between molecules :confused:
 
If there were no forces between the molecules, why would it take any work to compress an ideal gas ?

The notion that an ideal gas has no intermolecular forces is common (even Wiki gets this wrong). But at the same time it is accepted that the molecules undergo elastic collisions. These two statements are in direct contradiction with each other. When molecules collide, they do experience forces. However, when the molecules are separated, the force between them is neglected.
 
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Also, if you think D is wrong (that in fact, there are no forces), how can you think that B is correct (that the force is linear is the distance) ?
 
i think if u read it from any compettitive exam book than it is just a fault ,otherwise it is very true that there r no intermolecular force between molecules of real gas
 
On the contrary there very much are intermolecular forces between real gases.
 
thanks for your explanation..but which one is the most suitable answer?or no answer at all?
 
B is the correct answer (meaning that it is the only incorrect statement).

The force is not linear in the separation, but that does not mean there is no force. The force vs. separation curve is zero everywhere except very near the origin, where it has a sharp spike.
 

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