Apentix/AP Chemistry/Unit 9: Applications of Thermodynamics/Question

AP Chemistrymediummcq1 pt

For a reversible reaction at equilibrium, what are the values of ΔG and ΔG°?

A.ΔG = 0, while ΔG° = −RT ln K is generally nonzero

B.Both ΔG and ΔG° equal zero

C.ΔG° = 0, while ΔG varies with concentration

D.Both track Q at every moment

Explanation

Core Concept

At equilibrium the forward and reverse processes balance and Q equals K, so the instantaneous driving force vanishes: ΔG = 0. Standard free energy is referenced differently, to hypothetical unit-concentration conditions, and equals −RT ln K. Unless K happens to be exactly 1, ΔG° stays nonzero at equilibrium; the two connect through ΔG = ΔG° + RT ln Q.

Correct Answer

AΔG = 0, while ΔG° = −RT ln K is generally nonzero

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