How Does Temperature Affect Equilibrium Constants for Conformers?

[krootox217]

Homework Statement

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?

Homework Equations

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

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?

 

[haruspex]

In the equation you quote, how is ΔG defined?