How Does Maxwell's Demon Relate to Entropy and Gas Separation?

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SUMMARY

This discussion clarifies the relationship between Maxwell's Demon, entropy, and gas separation in the context of thermodynamics. It establishes that when a mixture of hydrogen and argon is released on a planet without an atmosphere, the hydrogen escapes due to its lower molecular weight, while argon remains, leading to an increase in entropy. The entropy of the system, which includes both the planet and the gases, increases as the gases expand, confirming that separation does not equate to a decrease in entropy.

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  • Understanding of the Second Law of Thermodynamics
  • Basic knowledge of gas behavior and properties
  • Familiarity with concepts of entropy and its measurement
  • Knowledge of Maxwell's Demon thought experiment
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  • Study the Second Law of Thermodynamics in detail
  • Research the concept of entropy and its implications in thermodynamic systems
  • Explore the Maxwell's Demon thought experiment and its interpretations
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Students of physics, educators teaching thermodynamics, and anyone interested in the principles of entropy and gas behavior in thermodynamic systems.

fluidistic
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Hi,
I've not covered yet the Second's Law of thermodynamics so I don't understand it well. A friend of mine talked to me about Maxwell's demon and now I have the following question :
Imagine a planet such that its escape velocity is about Earth's one, but without any atmosphere. Now imagine I have a composed gas (hydrogen+argon) and I free it at ground level. After some time all the hydrogen would leave out the planet and the argon would remain on the planet. So without any intervention the 2 gases are separated. How has the entropy increased?
Thank you.
 
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There's no conflict here- both gases expand, and the entropy of the system (planet+ gases) is proportional to the volume occupied.
 
Andy Resnick said:
There's no conflict here- both gases expand, and the entropy of the system (planet+ gases) is proportional to the volume occupied.

Ah ok!
I thought that by separating the 2 gases the entropy would have decreased. Anyway I'll be soon studying the second law of thermodynamics so I guess I will understand what is entropy and understand better the example I gave here.
Thank you for the answer. (so there's no ambiguity, no paradox nor anything wrong with the situation described above).
 

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