Equilibrium constant from ΔG°
At 298 K, ΔG° = −2.303RT log K, and 2.303RT ≈ 5.7 kJ/mol. If ΔG° = −5.7 kJ/mol, what is K?
Answer C: explanation for every choice
A
This reverses the sign. A negative ΔG° gives K greater than 1.
B
K = 1 corresponds to ΔG° = 0.
C
Correct. log K = −ΔG°/(2.303RT) = 5.7/5.7 = 1, so K = 10.
D
This corresponds to ΔG° = −11.4 kJ/mol (log K = 2).
TakeawayAt 298 K, each −5.7 kJ/mol in ΔG° multiplies K by 10.
Equation usedFree energy and the equilibrium constant
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