Finding entropy change when house leaks heat

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Homework Help Overview

The discussion revolves around calculating the change in entropy when heat leaks from a house. The temperatures inside and outside the house are provided, along with the amount of heat lost.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss the calculation of entropy change using the heat transfer and temperatures involved. Questions arise regarding whether to include the entropy change of the house itself in the calculation.

Discussion Status

Some participants have offered guidance on considering both the loss of entropy from the house and the gain from the outside environment. There is acknowledgment of the need to clarify the total change in entropy as the sum of both contributions.

Contextual Notes

Participants note potential ambiguity in the problem statement regarding the total entropy change being sought, leading to discussions about the correct approach to the calculation.

rubenhero
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Homework Statement


b) The temperature inside a house is Tin = 19.2° C when the temperature outside is Tout = 10.7° C. If Q = 5.49 kJ of heat leak from the house to the outside, find the change in entropy caused by this process.


Homework Equations


W = QH - QC, dS = dQ/T


The Attempt at a Solution


dS = 5.49kJ/283.7K = .0193514276kJ/K

The answer I calculated was wrong, should I include the entropy inside the house?
Any help is appreciated!
 
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Hi rubenhero! :smile:

rubenhero said:

Homework Statement


b) The temperature inside a house is Tin = 19.2° C when the temperature outside is Tout = 10.7° C. If Q = 5.49 kJ of heat leak from the house to the outside, find the change in entropy caused by this process.


Homework Equations


W = QH - QC, dS = dQ/T


The Attempt at a Solution


dS = 5.49kJ/283.7K = .0193514276kJ/K

The answer I calculated was wrong, should I include the entropy inside the house?
Any help is appreciated!

Inside you lose ΔS=-Q/TH.
Outside you gain ΔS=Q/TL.

The question in your problem statement is not entirely clear, but I suspect the total change in entropy is intended, which is the sum of both entropy changes.
 
Thanks you for responding. You were right, I just did the sum of the entropy loss and gain and got an answer of .5629265733 J/K. Webassign marked my answer as right. Thanks again for your help!
 
You're welcome! :)
 

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