How Does Temperature Affect Equilibrium Constants for Conformers?

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In summary, the question asked about the Keq at two different temperatures and the provided equations were used to calculate the values. However, a mistake was made in using the value for ΔΔG instead of ΔG, resulting in incorrect values for Keq. Assistance is requested in solving the problem correctly.
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krootox217
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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?
 
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In the equation you quote, how is ΔG defined?
 

FAQ: How Does Temperature Affect Equilibrium Constants for Conformers?

What is Keq and why is it important?

Keq, or the equilibrium constant, is a measure of the ratio of products to reactants at equilibrium in a chemical reaction. It is important because it tells us the direction and extent of a reaction under a specific set of conditions.

How do you calculate Keq?

Keq can be calculated by taking the ratio of the concentrations of products to the concentrations of reactants, with each concentration raised to the power of its coefficient in the balanced chemical equation. Alternatively, it can also be calculated using the equilibrium expressions for gases or for aqueous solutions.

What is the significance of calculating Keq at different temperatures?

Temperature can greatly affect the value of Keq for a chemical reaction. As temperature increases, the value of Keq also increases, indicating a higher concentration of products at equilibrium. Conversely, a decrease in temperature leads to a decrease in Keq, indicating a higher concentration of reactants at equilibrium.

How does the value of Keq change between room temperature and -78°C?

The value of Keq generally increases as temperature decreases. Therefore, at -78°C, the value of Keq would likely be higher than at room temperature. This means that there would be a higher concentration of products at equilibrium at -78°C compared to room temperature.

Can the value of Keq change over time?

The value of Keq does not change over time. It is a constant value at a specific temperature and set of conditions. However, the concentrations of products and reactants may change over time as the reaction proceeds towards equilibrium, which can affect the calculated value of Keq.

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