Problem on entropy change and specific heat capacity

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Homework Help Overview

The discussion revolves around calculating the change in entropy of the Universe due to the interaction between a copper block and a lake. The problem involves concepts from thermodynamics, specifically entropy change and specific heat capacity.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • The original poster attempts to apply equations for entropy change and heat transfer but questions the validity of the thermal capacity provided. Some participants question whether the given mass is relevant or if it could be a distraction.

Discussion Status

The discussion has evolved with some participants providing guidance on the interpretation of the thermal capacity. There are multiple interpretations being explored regarding the relevance of the mass and the nature of the thermal capacity.

Contextual Notes

Participants are navigating potential ambiguities in the problem setup, particularly concerning the units of thermal capacity and the implications of the mass of the copper block.

con31773
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Calculate the change in entropy of the Universe as a result of the following
operations:
(a) A copper block of mass 0.4kg and thermal capacity 150JK-1 at 100◦C is
placed in a lake at 10◦C.

dS=dQ/T dQ=mCdT

Tried simply combining these equations and integrating to find change of entropy of block. Knowing that final temperature of the block will be approximately the initial temperature of the lake. So we get
mc[ln(T)] between boundaries of T1 and T2. However, this thermal capacity does not have the standard units for c, which is JK-1Kg-1, so I am questioning my whole approach. Assuming this is just some typo perhaps and I do indeed do this, I am not sure on how to find the universal entropy change. Any help would be greatly appreciated.
Many thanks in advance.
 
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It's an obvious typo, so, what is the change in entropy of the block?
How much heat is transferred from the block to the lake?
At what temperature does the lake receive this heat?
What is the change in entropy of the lake?
What is the total change in entropy for the block plus lake?

Chet
 
Does it have to be a typo? The 0.4kg could just be a red herring.
 
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rude man said:
Does it have to be a typo? The 0.4kg could just be a red herring.
True. Who knows?

Chet
 
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It turns out It wasn't a typo, the C here was the heat transfer per unit temperature (multiple of C and M), something I was not familiar with. As a result the the question becomes much simpler, just being the sum of the two entropy change (block and lake)
Your help was much appreciated :)
 

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