Key words: high temperature adiabatic calorimeter; isochoric heat capacity; critical point; supercritical fluids; equation of state
This review presents the results of a detailed analysis of the role of isochoric heat
capacity as a key thermodynamic property of a substance in the study of critical and
supercritical phenomena. A brief historical background is given on the role and
contribution of Russian scientific schools in the experimental study of isochoric heat
capacity in the critical region in the development of the non-classical (scaling) theory
of critical phenomena, which considerably changed our understanding of the physical
nature of critical and supercritical phenomena. The experimental behavior of the
isochoric heat capacity and other thermodynamic properties of fluids associated with
it in the critical and supercritical regions are analyzed in detail. The role of new
experimental studies of two-phase isochoric heat capacity near the critical point in
the development of a “complete” scaling theory is discussed. This theory allows to
understand the physical nature of the liquid-gas coexistence curve asymmetry near
the critical point and to estimate the contribution of the chemical potential to the
divergence of the two-phase isochoric heat capacity at the critical point. The review
also focuses on supercritical phase transitions and the role of isochoric heat capacity
in determining the Widom line, which separates liquid- and gas-like regions in
supercritical states, i.e. defines the boundaries of the coexistence of “liquid-” and “gaslike”
phases in supercritical fluids.
doi:10.1134/S1990793120070192