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Suppose a compound could point in any two directions in the solid and still have the

  1. May 4, 2010 #1
    1. The problem statement, all variables and given/known data
    Suppose a compound could point in any two directions in the solid and still have the same energy. How many molecules would there be if the total entropy of a solid sample of this compound was 1.181x10^-12 J/K?



    2. Relevant equations
    My plan that failed -

    S = k*ln(W),
    where S is entropy
    k is Boltzman constant = 1.38 x 10-23 (J/K) or equivalent to (Universal Gas Constant 8.314/Avogadro's number 6.02 x 1023 molecules/mol)
    W is the number of microstates

    3. The attempt at a solution



    1.181x10^-12 J/K = (8.314/ x 6.02*1023)*(ln(2)), I put 2 in ln(2) because I thought the question stated the total microstates when it said "...point in any two directions".

    I solved for x and got 3.242e13 which is wrong.
     
  2. jcsd
  3. May 6, 2010 #2

    Redbelly98

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    Re: Suppose a compound could point in any two directions in the solid and still have

    Welcome to Physics Forums.

    It would be 2 microstates if there were just 1 molecule. With many molecules, there are many many possible combinations of their orientations.

    Treat W as an unknown, and solve for it. Once you have W, the final step will be to figure out how many molecules.
     
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