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Homework Help: Finding Entropy

  1. Jun 18, 2014 #1
    1. The problem statement, all variables and given/known data

    "see attachment"

    2. Relevant equations

    Change in entropy = Boltzmann Constant x In(Macrostate)

    3. The attempt at a solution

    for part A, I knew that PV=NKbT

    giving that pressure is 101300Pa volume is 1*10^-3 m^3, Kb is 1.38*10^-23 and T=300K
    I find N to be 2.446*10^22 atoms

    the problem I have is with part B

    the question states that microstate is proportion to V^N where N is the number of atom I found in part A, and V is the volume which is 1*10-9 m^3. Thus V^N is a very small number which is pretty much zero. Change in entropy = Boltzmann Constant x In(Macrostate), since Macrostate is zero, there is an error in this calculation. Since In(0) is undefined. What am I suppose to do in this question??
  2. jcsd
  3. Jun 18, 2014 #2
    I forgot to attach the question, here it is

    Attached Files:

  4. Jun 20, 2014 #3
    Hi Junkwisch!

    Always in physics things are only big or small relative to other things. The numerical value of [itex]V^N[/itex] depends entirely on what units you're using.

    Perhaps you can simplify [itex]\ln\left(V^N\right)[/itex] without making an approximation? :smile:
  5. Jun 20, 2014 #4


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    You should check that you have the correct relationship here. How can the left side of the equation be a change when there's no corresponding change present on the righthand side of the equation? Also, what is "Macrostate" supposed to represent?
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