What happens to the value of K when ΔG becomes more positive?

Prepare for the ACS Physical Chemistry: Thermochemistry Test with detailed questions, flashcards, hints, and explanations. Get ready to excel in the exam!

The value of the equilibrium constant, K, is related to the change in Gibbs free energy, ΔG, through the equation:

[

ΔG = ΔG^\circ + RT \ln Q

]

At equilibrium, ΔG equals zero, and this leads to the relationship:

[

0 = ΔG^\circ + RT \ln K

]

From this equation, we can derive that:

[

ΔG^\circ = -RT \ln K

]

This indicates that if ΔG becomes more positive, ΔG^\circ must also become more positive. A more positive ΔG^\circ indicates that the reaction is less favorable in the forward direction. Since ΔG^\circ is inversely related to K through the equation, a more positive ΔG^\circ will result in a smaller value of K. This means the equilibrium position favors the reactants over the products, reflecting a decrease in K.

Thus, as ΔG becomes more positive, the value of K indeed gets smaller, confirming the validity of the answer.

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