Does Isothermal Heat Flow Out Contradict the Second Law of Thermodynamics?

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Homework Help Overview

The discussion revolves around the concept of isothermal heat flow and its relationship with the second law of thermodynamics. Participants are exploring how heat flow from a system can lead to a decrease in entropy without violating thermodynamic principles.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are examining the definition of "system" in the context of thermodynamics and discussing how heat flow affects entropy in both the system and its surroundings. There is an exploration of the relationship between the entropy changes of the system and the environment during a reversible process.

Discussion Status

The conversation is ongoing, with some participants providing insights into the balance of entropy changes between the system and the surroundings. There is recognition of the need to consider the entire system when discussing entropy changes, but no explicit consensus has been reached.

Contextual Notes

Participants are navigating the implications of the second law of thermodynamics and the definitions of system and surroundings, which may lead to varying interpretations of the concepts involved.

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Homework Statement



When there is a heat flow out of the system during a reversible isothermal processthe entropy of the system decreases.Why does this not violate the 2nd law of thermodynamics?

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The Attempt at a Solution

I hope this is correct.Please check and confirm.


Because the question uses the word "system" quite loosely. They are using "system" to mean the gas or other working substance from which the heat flows. But in terms of the second law, the word "system" refers to everything that loses or gains heat during the process.

So while the gas releases heat and the entropy of the gas decreases, the heat is absorbed by the environment (which must be included in the "system") and the entropy of the environment increases. Overall the total change in entropy is positive, as the increase for the environment is greater than the decrease for the gas.
 
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when there is a decrease in this enrophy, the entropy of the surroundings increases, u are quite right. system in the law refers to everything
 
OK thank you.
 
In fact, if it's reversable, then the entropy increase of the surroundings exactly matches the entropy decrease of the system.
 

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