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The standard Gibbs free energy of formation (G f °) of a compound is the change of Gibbs free energy that accompanies the formation of 1 mole of a substance in its standard state from its constituent elements in their standard states (the most stable form of the element at 1 bar of pressure and the specified temperature, usually 298.15 K or 25 °C).
The state of aggregation for thermodynamic purposes is the standard state, sometimes called the reference state, and defined by specifying certain conditions. The normal standard state is commonly defined as the most stable physical form of the substance at the specified temperature and a pressure of 1 bar or 1 atm. However, since any non ...
The standard Gibbs free energy of formation of a compound is the change of Gibbs free energy that accompanies the formation of 1 mole of that substance from its component elements, in their standard states (the most stable form of the element at 25 °C and 100 kPa). Its symbol is Δ f G˚.
Helmholtz free energy: A, F = J ML 2 T −2: Landau potential, Landau free energy, Grand potential: Ω, Φ G = J ML 2 T −2: Massieu potential, Helmholtz free entropy: Φ = / J⋅K −1: ML 2 T −2 Θ −1: Planck potential, Gibbs free entropy: Ξ
Molar Gibbs free energy is commonly referred to as chemical potential, symbolized by , particularly when discussing a partial molar Gibbs free energy for a component in a mixture. For the characterization of substances or reactions, tables usually report the molar properties referred to a standard state .
Several free energy functions may be formulated based on system criteria. Free energy functions are Legendre transforms of the internal energy. The Gibbs free energy is given by G = H − TS, where H is the enthalpy, T is the absolute temperature, and S is the entropy. H = U + pV, where U is the internal energy, p is the pressure, and V is the ...
Standard Gibbs free energy of formation; H. Helmholtz free energy; M. Miedema's model This page was last edited on 10 May 2022, at 07:04 (UTC). Text is available ...
An equilibrium constant is related to the standard Gibbs free energy change for the reaction = R is the gas constant and T is the absolute temperature. At 25 °C, ΔG ⊖ = (−5.708 kJ mol −1) ⋅ log β. Free energy is made up of an enthalpy term and an entropy term.