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In thermodynamics, the phase rule is a general principle governing multi-component, multi-phase systems in thermodynamic equilibrium.For a system without chemical reactions, it relates the number of freely varying intensive properties (F) to the number of components (C), the number of phases (P), and number of ways of performing work on the system (N): [1] [2] [3]: 123–125
Where is is the surface energy of the two-phase boundary, is the molar volume of the eutectic phase, is the solidification temperature of the eutectic phase, is the enthalpy of formation of the eutectic phase, and is the undercooling of the material. So, by altering the undercooling, and by extension the cooling rate, the minimal achievable ...
This equal area rule can also be derived by making use of the Helmholtz free energy. [24] In any event the Maxwell construction derives from the Gibbs condition of material equilibrium. However, even though g f = g g {\displaystyle g_{f}=g_{g}} is more fundamental it is more abstract than the equal area rule, which is understood geometrically.
Gibbs's paper marked the beginning of chemical thermodynamics by integrating chemical, physical, electrical, and electromagnetic phenomena into a coherent system. It introduced concepts such as chemical potential , phase rule , and more, which form the basis for modern physical chemistry.
A miscibility gap between isostructural phases may be described as the solvus, a term also used to describe the boundary on a phase diagram between a miscibility gap and other phases. [2] Thermodynamically, miscibility gaps indicate a maximum (e.g. of Gibbs energy) in the composition range. [3] [4]
When pressure and temperature are variable, only of components have independent values for chemical potential and Gibbs' phase rule follows. The Gibbs−Duhem equation cannot be used for small thermodynamic systems due to the influence of surface effects and other microscopic phenomena. [2] The equation is named after Josiah Willard Gibbs and ...
Calculating the number of components in a system is necessary when applying Gibbs' phase rule in determination of the number of degrees of freedom of a system. The number of components is equal to the number of distinct chemical species (constituents), minus the number of chemical reactions between them, minus the number of any constraints ...
In thermodynamics, the Gibbs free energy (or Gibbs energy as the recommended name; symbol ) is a thermodynamic potential that can be used to calculate the maximum amount of work, other than pressure–volume work, that may be performed by a thermodynamically closed system at constant temperature and pressure.