How do I state 2nd law of thermodynamics for an open system

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Discussion Overview

The discussion revolves around the application of the second law of thermodynamics to open systems, particularly in the context of ecosystems. Participants explore how energy and materials are exchanged with the environment and the implications for thermodynamic laws.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant notes that ecosystems are open systems that receive solar energy and materials from outside, questioning how to state the second law of thermodynamics in this context.
  • Some participants assert that there is neither a second law nor a first law for open systems, suggesting that this is incorrect.
  • Another participant proposes that balance equations can be established for energy and entropy in open systems, indicating that entropy transport terms can be both positive and negative, while entropy production terms must be positive due to the second law.
  • A later reply emphasizes the existence of balance equations, correcting earlier claims about the absence of thermodynamic laws for open systems.

Areas of Agreement / Disagreement

Participants express disagreement regarding the applicability of the first and second laws of thermodynamics to open systems, with some asserting their absence while others argue for the existence of balance equations that incorporate these laws.

Contextual Notes

Participants reference specific literature on thermodynamics and ecosystems, but there is no consensus on how to formally state the second law for open systems, and the discussion includes varying interpretations of thermodynamic principles.

Tyto alba
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Ecosystems are open systems, they receive solar energy and other materials from outside the ecosystem and migration of animals is also witnessed.

I read Physics uptil class XII and have done a bit of research on google books and have come across these three books:

1.Towards a Thermodynamic Theory for Ecological Systems, pg-41

2.Thermodynamics of Non-Equilibrium Processes for Chemists, pg-9

3.Ecosystem Ecology, pg-35

P.S. I couldn't come up with anything statement.
I'm not sure if I posted on the right sub-forum. Let me know if this is suitable to other sub-forums and tell me why do you think so.
 
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There is neither 2nd law nor 1st law for an open system.
 
You can set up bilance equations for energy entropy etc. The one for entropy contains both transport terms (e.g. when an animal enters or leaves your system) which can be positive and negative and entropy production terms which can only be positive, due to the second law.
 
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Demystifier said:
There is neither 2nd law nor 1st law for an open system.
This is not correct.
 
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Demystifier said:
There is neither 2nd law nor 1st law for an open system.

Of course there is- usually written as balance equations.
 
SanjuktaGhosh said:
Ecosystems are open systems, they receive solar energy and other materials from outside the ecosystem and migration of animals is also witnessed.

I read Physics uptil class XII and have done a bit of research on google books and have come across these three books:

1.Towards a Thermodynamic Theory for Ecological Systems, pg-41

2.Thermodynamics of Non-Equilibrium Processes for Chemists, pg-9

3.Ecosystem Ecology, pg-35

P.S. I couldn't come up with anything statement.
I'm not sure if I posted on the right sub-forum. Let me know if this is suitable to other sub-forums and tell me why do you think so.

As DrDu mentioned, there are balance equations that can be written down, a crude version for entropy is here:

http://www.learnthermo.com/T1-tutorial/ch08/lesson-B/pg04.php
 
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Andy Resnick said:
Of course there is- usually written as balance equations.
Thanks for the correction! :woot:
 
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