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Gibbs-Helmholtz equation[′gibz ′helm‚hōlts i‚kwā·zhən]
An expression for the influence of temperature upon the equilibrium constant of a chemical reaction, (d ln K °/ dT) P = Δ H °/ RT 2, where K ° is the equilibrium constant, Δ H ° the standard heat of the reaction at the absolute temperature T, and R the gas constant.
Either of two thermodynamic relations that are useful in calculating the internal energy U or enthalpy H of a system; they may be written U = F-T (∂ F /∂ T) V and H = G-T (∂ G /∂ T) P, where F is the free energy, G is the Gibbs free energy, T is the absolute temperature, V is the volume, and P is the pressure.
Any of the similar equations for changes in thermodynamic potentials during an isothermal process.