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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
This violation is not a defect, rather it is the origin of the observed discontinuity in properties that distinguish liquid from vapor, and defines a first order phase transition. Figure 1: The curve is an isotherm, constant, in the --plane of a fluid that includes a phase change. The various segments of the curve are described in the text.
In physics, chemistry, and other related fields like biology, a phase transition (or phase change) is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic states of matter : solid , liquid , and gas , and in rare cases, plasma .
Equality of chemical potential defines chemical equilibrium. Other constants for dynamic equilibrium involving phase changes, include partition coefficient and solubility product. Raoult's law defines the equilibrium vapor pressure of an ideal solution. Dynamic equilibrium can also exist in a single-phase system.
Phase transitions and critical exponents appear in many physical systems such as water at the critical point, in magnetic systems, in superconductivity, in percolation and in turbulent fluids. The critical dimension above which mean field exponents are valid varies with the systems and can even be infinite.
Mathematically, = =, where / is the slope of the tangent to the coexistence curve at any point, is the molar change in enthalpy (latent heat, the amount of energy absorbed in the transformation), is the temperature, is the molar volume change of the phase transition, and is the molar entropy change of the phase transition. Alternatively, the ...
where α is an exponent specific to the system (e.g. in the absence of a potential field, α = 3/2), z is exp(μ/k B T) where μ is the chemical potential, Li is the polylogarithm, ζ is the Riemann zeta function, and T c is the critical temperature at which a Bose–Einstein condensate begins to form.
In chemistry, Le Chatelier's principle (pronounced UK: / l ə ʃ æ ˈ t ɛ l j eɪ / or US: / ˈ ʃ ɑː t əl j eɪ /) [1] is a principle used to predict the effect of a change in conditions on chemical equilibrium. [2] Other names include Chatelier's principle, Braun–Le Chatelier principle, Le Chatelier–Braun principle or the equilibrium ...