Quick question about perfect gas

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Homework Help Overview

The discussion revolves around the behavior of a mixture of helium and krypton as a perfect gas, specifically focusing on the conditions under which this assumption holds true. Participants are examining the relationship between the average values of mass, momentum, velocity, and kinetic energy of the gas atoms.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are questioning which property must be equal for the gases to behave as a perfect gas, with discussions centering on kinetic energy and the implications of temperature. There is also a consideration of thermal equilibrium and its relevance to the properties of the gas mixture.

Discussion Status

The conversation is active, with participants sharing their thoughts on the properties of gases and exploring the implications of thermal equilibrium. There is a recognition of differing opinions regarding the relevance of mass and kinetic energy, but no consensus has been reached yet.

Contextual Notes

Participants are operating under the assumption that the gases are at the same temperature, which influences their reasoning about kinetic energy and thermal properties. There is also an acknowledgment of the complexities involved in defining a perfect gas mixture.

criticalPoint
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Two different gasses (Helium and Cripton) are mixed up. We can assume the compound behaves as a perfect gas only if the atoms of He and Kr have the same average value of:
  • Mass
  • Momentum
  • Velocity
  • Kinetic energy
Which one is correct? I can't figure it out.
 
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Which one do you think it is and why? Let's start there.
 
Obviously it's not mass (average mass can't be equal in any circumnstances), because they are at the same temperature I suppose they have the same kinetic energy, but wouldn't that happen for every kind of mixture? I can't undestand what specific property of a perfect gas is important here, what makes this mixture perfect and not real.
 
criticalPoint said:
Obviously it's not mass (average mass can't be equal in any circumnstances)
I agree about mass.
criticalPoint said:
because they are at the same temperature I suppose they have the same kinetic energy, but wouldn't that happen for every kind of mixture? I can't undestand what specific property of a perfect gas is important here, what makes this mixture perfect and not real.
Not necessarily. Maybe after a long period of time every mixture will be in thermal equilibrium, but it doesn't have to be the case. I agree thermal equilibrium is a property which would imply the same kinetic energy. What are the other properties? Can they help us here?
 

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