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When both temperature and pressure are held constant, and the number of particles is expressed in moles, the chemical potential is the partial molar Gibbs free energy. [1] [2] At chemical equilibrium or in phase equilibrium, the total sum of the product of chemical potentials and stoichiometric coefficients is zero, as the free energy is at a ...
Each quantity in the equations above can be divided by the amount of substance, measured in moles, to form molar Gibbs free energy. The Gibbs free energy is one of the most important thermodynamic functions for the characterization of a system.
This means that the partial molar Gibbs free energy and the chemical potential, one of the most important properties in thermodynamics and chemistry, are the same quantity. Under isobaric (constant P) and isothermal (constant T ) conditions, knowledge of the chemical potentials, (,,,), yields every property of the mixture as they completely ...
The Gibbs−Duhem equation applies to homogeneous thermodynamic systems. It does not apply to inhomogeneous systems such as small thermodynamic systems, [2] systems subject to long-range forces like electricity and gravity, [3] [4] or to fluids in porous media. [5] The equation is named after Josiah Willard Gibbs and Pierre Duhem.
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 .
The excess partial molar Gibbs free energy is used to define the activity coefficient, ... This formula can be used to compute the excess volume from a pressure ...
[4]: 215 In other words, the temperature, pressure and molar Gibbs free energy are the same between the two phases when they are at equilibrium. An equivalent, more common way to express the vapor–liquid equilibrium condition in a pure system is by using the concept of fugacity. Under this view, equilibrium is described by the following equation: