9.5 Free Energy and Equilibrium

Explain whether a process is thermodynamically favored using the relationships between K, ΔGo, and T.

• The phrase “thermodynamically favored” (ΔGo < 0) means that the products are favored at equilibrium (K > 1) under standard conditions.
• The equilibrium constant is related to free energy by the equations EQN: K = e−ΔG°/RT and EQN: ΔG° = −RT ln K.
• Connections between K and ΔG° can be made qualitatively through estimation. When ΔG° is near zero, the equilibrium constant will be close to 1. When ΔG° is much larger or much smaller than RT, the value of K deviates strongly from 1.
• Processes with ΔG° < 0 favor products (i.e., K > 1) and those with ΔG° > 0 favor reactants (i.e., K < 1).