Gibbs–Helmholtz Equation
The relation showing how the Gibbs free energy of a system varies with temperature.
Formula / equation
(∂(ΔG/T)/∂T)_p = −ΔH/T²
Unit
kJ/mol
In depth
The equation lets a free energy change known at one temperature be converted to another, provided the enthalpy change is known and roughly constant. It underpins the van't Hoff analysis of how equilibrium constants shift with temperature.
Examples in the real world
Predicting how the equilibrium constant of ammonia synthesis falls as the reactor temperature is raised.