Problem on entropy change and specific heat capacity

AI Thread Summary
The discussion revolves around calculating the change in entropy of a copper block when placed in a lake, addressing the confusion over the thermal capacity units. Initially, the user attempted to integrate the equations for entropy change but questioned the thermal capacity's standard units. Clarification revealed that the given thermal capacity was indeed correct and represented heat transfer per unit temperature. The solution simplifies to calculating the total entropy change by summing the changes for both the block and the lake. The conversation highlights the importance of understanding specific heat capacity in entropy calculations.
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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