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Homework Help: Calculation of Keq

  1. Apr 27, 2017 #1
    1. The problem statement, all variables and given/known data
    Hi, I have the following task:

    We have two conformers and the difference in energy between them is aprox. 1 Kcal/mol. What is the Keq at room temperature vs. at -78°C?

    2. Relevant equations


    3. The attempt at a solution

    I tried to solve the problem the following way:

    deltaG = R*T*ln(Keq) --> Keq=e^(deltaG/(-R*T))

    T(room)=293.15K, T(-78°C)=195.15K
    R=8.313 J/(mol*K), DeltaG= 1 Kcal/mol= 4184 J/mol

    then I inserted the values and got Keq(room) = 0.18 and Keq(-78°C) = 0.08 which is apparently wrong. They told me that I used deltadeltaG instead of deltaG in the equation. Can somebody help me?
  2. jcsd
  3. May 1, 2017 #2


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    Science Advisor
    Homework Helper
    Gold Member

    In the equation you quote, how is ΔG defined?
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