Chemical potential

In thermodynamics, the chemical potential of a species is the energy that can be absorbed or released due to a change of the particle number of the given species, e.g. in a chemical reaction or phase transition. The chemical potential of a species in a mixture is defined as the rate of change of free energy of a thermodynamic system with respect to the change in the number of atoms or molecules of the species that are added to the system. Thus, it is the partial derivative of the free energy with respect to the amount of the species, all other species' concentrations in the mixture remaining constant. 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 minimum.[3][4][5] In a system in diffusion equilibrium, the chemical potential of any chemical species is uniformly the same everywhere throughout the system.[6]

In semiconductor physics, the chemical potential of a system of electrons at zero absolute temperature is known as the Fermi level.[7]

  1. ^ Atkins 2006[page needed]
  2. ^ Opacity, Walter F. Huebner, W. David Barfield, ISBN 1461487978, p. 105.
  3. ^ Atkins 2002, pp. 227, section 9.2
  4. ^ Baierlein, Ralph (April 2001). "The elusive chemical potential" (PDF). American Journal of Physics. 69 (4): 423–434. Bibcode:2001AmJPh..69..423B. doi:10.1119/1.1336839.
  5. ^ Job, G.; Herrmann, F. (February 2006). "Chemical potential–a quantity in search of recognition" (PDF). European Journal of Physics. 27 (2): 353–371. Bibcode:2006EJPh...27..353J. CiteSeerX 10.1.1.568.9205. doi:10.1088/0143-0807/27/2/018. S2CID 16146320. Archived from the original (PDF) on 2015-09-24. Retrieved 2009-02-12.
  6. ^ Atkins 2002, pp. 141, section 6.4
  7. ^ Kittel 1980, pp. 357