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Homework Help: Calculate the change in entropy of the cube-lake system

  1. Jul 1, 2009 #1
    A 11 g ice cube at -20°C is placed in a lake whose temperature is 13°C. Calculate the change in entropy of the cube-lake system as the ice-cube comes into thermal equilibrium with the lake. The specific heat of ice is 2220 J/kg*K. (Hint: Will the ice cube affect the temperature of the lake?)

  2. jcsd
  3. Jul 1, 2009 #2


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    Show work.
  4. Jul 1, 2009 #3
    i have no idea how to calculate this... at all.. T_T
  5. Jul 1, 2009 #4

    Andrew Mason

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    Start by giving us the expression for the change in entropy dS due to an infinitessimal heat flow dQ.

    What is the final temperature of the water molecules that are contained in the ice cube? Where does that heat flow come from?

    How much heat has to flow? Use the expression for dS to work out the total entropy change for the lake.

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