Isochoric heat capacity of near– and supercritical benzene and derived thermodynamic properties

Published

June 8, 2020

Author(s)

Nikolai Polikhronidi, Rabiyat Batyrova, Joe W. Magee, Ilmutdin Abdulagatov

Abstract

As part of a continuing study of the critical and supercritical phenomena in the fluids and fluid mixtures, one-phase and two-phase isochoric heat capacities, densities and phase- transition temperatures of benzene were measured in the critical and supercritical regions. Measurements were made in the immediate vicinity of the liquid-gas phase transition and the critical points in order to accurately determine of phase transition properties. The measurements cover the temperature range from (347 to 616) K for 10 liquid and vapor isochores between (265 and 653) kgm-3 at pressure up to 7.5 MPa. The measurements were performed using a high-temperature, high-pressure, nearly constant-volume adiabatic calorimeter. The combined expanded uncertainties of the density, temperature, and isochoric heat capacity measurements at the 95 % confidence level with a coverage factor of k = 2 are estimated to be 0.15 %, 15 mK, and 3 %, respectively. The measurements near the critical point were used to estimate the theoretically meaningful asymptotic critical amplitudes, amplitudes for other properties and their universal relations. Saturated liquid and vapor densities together with measured two- phase data were used to estimate the values of asymmetric parameters ("complete" scaling parameter) and of the coexistence curve singular diameter. Experimentally determined asymptotical critical amplitudes were used to check and confirm the predictive capability of the universal correlation in terms of their dependence on the acentric factor based on the generalized corresponding states principle. The measured values of two-phase as a function of the specific volume V along various isotherms were used to calculate second temperature derivatives of vapor pressure and chemical potential and to estimate the value of Yang-Yang anomaly strength parameter for benzene. The contributions of the vapor-pressure and the chemical potential to the measured total two-phase heat capacity were estimated.

Citation

Journal of Molecular Liquids

Volume

313

Pub Type

Journals

Download Paper

https://doi.org/10.1016/j.molliq.2020.113204

Local Download

Keywords

Adiabatic calorimeter, Asymmetric parameter, Benzene, Critical amplitude, Critical point, Isochoric heat capacity, Yang-Yang anomaly parameter

Citation

Polikhronidi, N. , Batyrova, R. , Magee, J. and Abdulagatov, I. (2020), Isochoric heat capacity of near– and supercritical benzene and derived thermodynamic properties, Journal of Molecular Liquids, [online], https://doi.org/10.1016/j.molliq.2020.113204, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=927538 (Accessed December 5, 2025)