Gibbs-Helmholtz equation


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Gibbs-Helmholtz equation

[′gibz ′helm‚hōlts i‚kwā·zhən]
(physical chemistry)
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.
(thermodynamics)
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.
References in periodicals archive ?
The differential sorption entropy was calculated using the Gibbs-Helmholtz equation 8 (Rizvi, 1995):
Values of entropy of adsorption ([DELTA][S.sub.ads]) were calculated by substituting corresponding values of [DELTA][G.sub.ads] and [DELTA][H.sub.ads] into the Gibbs-Helmholtz equation according to Equation 10: (Abdallah, M., 202; Bilgic, L.,2001)
Energetics II: Entropy and free energy: Gibbs-Helmholtz equation; standard free energy of formation; calculating |DELTA~ |G.sup.O~ from tables; |DELTA~ G vs.