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Boltzmann Distribution (Chemistry/ Physics)

  1. Jan 8, 2013 #1
    1. The problem statement, all variables and given/known data
    Okay i want to ask 2 questions.
    Question 1
    Hyperstoichiometric compound Al3O has a vibrational energy spacing of 3.08x 10^-21J
    how many molecules are present in the ground state at 300k and 3000K

    Question 2
    Calirimetric data for protein unfolding yielded following thermodynamic parameters
    Parameter
    ΔH (Tr) 220kJ/mol
    ΔS (Tr) 0.68 kJ/mol/K
    ΔCp 2.5 kJ/mol/K
    how many protein molecules unfolded at 300K
    2. Relevant equations
    For question 1
    Shown below is the boltzmann equation
    nj/ni = e-(Ej-Ei)/KT

    Grond state equation is
    nj/n0 = e-(Ej)/KT (this I found in a text book)

    For question 2

    ΔG=ΔH-TΔS


    3. The attempt at a solution

    Okay for question the equation given in lecture notes is different to the equation i found in text books and the internet and it is

    n0 = n(1-e-(ΔE)/KT

    Two equations are confusing me, the this is if i use the equation given under relevant equations I get a weird answer,obviously wrong. Using the equation given in lecture notes it is easy and straight forward, but i doubt if it correct!

    and for question 2 i have no clue what so ever to be honest. I do not know how i can use ΔCp

    Thank you very much in advance for your help
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
    Last edited: Jan 8, 2013
  2. jcsd
  3. Jan 9, 2013 #2

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    With the Boltzmann equation, you would have to consider all states (and add their relative probabilities), as this just gives a relative probability. Your equation at (3.) did take this into account, you can use it.

    Question 2: No idea.
     
  4. Jan 10, 2013 #3
    Question 2 looks like fun! :biggrin:

    Think about what the link between ΔS and CP ([itex]\Delta S = nC_p ln\frac{T}{T_0}[/itex]) means for the system.
     
  5. Jan 11, 2013 #4
    thanx guys, question 2 is fun and an absolute killer
     
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