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Homework Help: Entropy of the universe

  1. May 1, 2012 #1
    1. The problem statement, all variables and given/known data
    Two large reservoirs, H and C, are available: if H is at 900 K and C is at 300 K, what is the
    entropy change of the Universe if 100 J of heat are taken from H and added to C?


    2. Relevant equations
    ΔS=∫dQ/T

    ΔS_universe = ΔS_surroundings + ΔS_system

    3. The attempt at a solution

    so it's just (-100/900)+(100/300) = 9/2 right? Just checking!
     
    Last edited: May 1, 2012
  2. jcsd
  3. May 1, 2012 #2

    collinsmark

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    I think that's the right approach. But isn't C at 300 K (not 200)?
    I think you might have inverted something.
     
  4. May 1, 2012 #3
    Sorry that 200 has been corrected to 300
     
  5. May 1, 2012 #4

    collinsmark

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    Okay, so we have...

    Okay, that looks correct. :approve:

    Wait, what?

    Try that simplification one more time. :wink:
     
  6. May 3, 2012 #5
    Sorry it's 2/9
     
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