Maxwell Relations
A set of thermodynamic equations derived from equality of second partial derivatives of thermodynamic potentials (U, H, F, G).
Governing formula
(∂T/∂V)_S = -(∂P/∂S)_V, (∂T/∂P)_S = (∂V/∂S)_P, etc.
SI unit
Various
In depth
Maxwell relations allow difficult-to-measure unobservable quantities like entropy S to be calculated from easily measurable state variables like P, V, and T.
Examples in the real world
Calculating entropy changes of compressed liquids directly from thermal expansion coefficients and compressibility.