Decrease in entropy and 2nd Law of Thermodynamics

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Discussion Overview

The discussion revolves around the concept of entropy in relation to the second law of thermodynamics, specifically addressing how a decrease in entropy of an object placed in a refrigerator can be reconciled with the law that states the total entropy of an isolated system cannot decrease. The scope includes theoretical considerations of thermodynamics and the functioning of refrigerators.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions how the decrease in entropy of a warm object in a refrigerator aligns with the second law of thermodynamics, which states that the total entropy of an isolated system cannot decrease.
  • Another participant argues that the refrigerator is not a closed system, as it transfers heat from inside to outside, thus affecting the overall entropy of the surrounding environment.
  • A third participant emphasizes that while the refrigerator cools its contents, it releases more heat into the room, generating greater entropy than the decrease experienced by the items inside the fridge, and notes the inefficiency of refrigerators.
  • A participant expresses gratitude to others for their contributions and inquires about their academic backgrounds.
  • One participant mentions their degree in Aesthetic Studies, which appears unrelated to the topic at hand.

Areas of Agreement / Disagreement

Participants generally agree that the refrigerator is not an isolated system and that the total entropy of the larger system (including the room) must be considered. However, there is no consensus on the implications of this for understanding the second law of thermodynamics in this context.

Contextual Notes

Participants have not fully resolved the implications of the refrigerator's operation on entropy, nor have they clarified the efficiency factors involved in its functioning.

Who May Find This Useful

This discussion may be of interest to those studying thermodynamics, physics students, or individuals curious about the principles of entropy and energy transfer in thermodynamic systems.

imy786
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General entrpy question from a book- (not a homework quesiton):

When a room temp object is placed in a refrigerator, heat flows out of object and its entropy decreases. Indeed, the refrigerator may be said to be a device for sucking entopy out of warm objects. How can such a decrease in entropy be consistent with the 2nd law of thermodynamics?

2nd law of thermodynamics:
The total entropy of an isolated system cannot decrase, it may increase.
 
Science news on Phys.org
Your refer' is pumping entropy into your kitchen...

Entropy in a closed system -- one where no energy crosses the boundary between system and not-system -- always increases. While the door of the refrigerator may be closed, it's not a closed system because heat is being transferred from inside to outside via the condenser you'll find someplace on the back.
 
The total entropy of an isolated system cannot decrease.

The fridge is not an isolated system by itself, it gives off heat so your system would (roughly) be the room enclosing the refrigerator. The heat the refrigerator is giving off generates more entropy than the cooling effect of the stuff in the fridge has decreasing entropy. This is because you need to consider the efficiency of the fridge. A fridge is not 100% efficient, nor can it ever be.
 
Thank you so much schip666! and Feldoh.

if you don't mind me asking are you both graduates in Physics or lecturers or other please do let me know. You may PM me if you want.

Thanks
 
I have a degree in Aesthetic Studies...
 

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