Thermodynamic Derivation of Scaling at the Liquid–Vapor Critical Point

Entropy

Victor Romero-Rochín¹  Juan Carlos Obeso-Jureidini¹  Daniela Olascoaga¹ 

[1] Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, Ciudad de México 01000, Mexico;

关键词: liquid–vapor critical point;    scaling hypothesis;    critical exponents;   

DOI  :  10.3390/e23060720

来源: DOAJ

【 摘 要 】

With the use of thermodynamics and general equilibrium conditions only, we study the entropy of a fluid in the vicinity of the critical point of the liquid–vapor phase transition. By assuming a general form for the coexistence curve in the vicinity of the critical point, we show that the functional dependence of the entropy as a function of energy and particle densities necessarily obeys the scaling form hypothesized by Widom. Our analysis allows for a discussion of the properties of the corresponding scaling function, with the interesting prediction that the critical isotherm has the same functional dependence, between the energy and the number of particles densities, as the coexistence curve. In addition to the derivation of the expected equalities of the critical exponents, the conditions that lead to scaling also imply that, while the specific heat at constant volume can diverge at the critical point, the isothermal compressibility must do so.

【 授权许可】

Unknown