ABSTRACT
This chapter presents some of the recent developments in the theory of critical-point phase transitions that have permitted a quantitatively correct description of critical-point anomalies in fluids. It seeks to indicate how the thermodynamic description of the critical behavior of one-component systems is generalized to include mixtures. The chapter discusses the characteristics of a critical point, and the properties of some models for critical point – phase transitions, namely the mean-field equation of state and the Ising model. It introduces the modern tools of critical-region description and presents power laws, critical exponents, homogeneity, scaling and universality. The study of classical critical behavior gives us the opportunity to introduce most concepts that are used in modern nonclassical descriptions of critical behavior. The chapter also discusses the experimental determination, description and scaling-law correlation of properties of one-component fluids. It is concerned with the critical behavior of mixtures and the generalization of the scaling approach to multicomponent systems.
