Science
Free energy and equilibrium.
Definition
Gibbs free energy (G) determines whether a reaction is spontaneous. At equilibrium, ΔG = 0 and the system has no net change. The relationship between free energy and the equilibrium constant is given by ΔG° = −RT ln K.
Examples
Real-world.
- 1 A reaction with a large negative ΔG° has a large K and strongly favors products
- 2 At equilibrium, forward and reverse reaction rates are equal and ΔG = 0
- 3 ATP hydrolysis has a negative ΔG, making it spontaneous and useful for cellular work
Key Fact
ΔG° = −RT ln K; when ΔG = 0, the system is at equilibrium