Gibbs-Helmholtz equations

$H=-T^{2}\left.{\frac {\partial (G/T)}{\partial T}}\right\vert _{p}$

$U=-T^{2}\left.{\frac {\partial (A/T)}{\partial T}}\right\vert _{V}$

where

• $H$ is the enthalpy
• $T$ is the temperature
• $G$ is the Gibbs energy function
• $U$ is the internal energy,
• $V$ is the volume
• $A$ is the Helmholtz energy function.