arXiv subjects

David A. Balzarini

Publications and source records attributed to David A. Balzarini.

2 recordsLinked to original sources

arXiv2006

Optical Studies of the coexistence curve of the n-heptane+nitrobenzene mixture near its consolute point measured by an optical method

We have measured the coexistence curve of the binary liquid mixture n-heptane+nitrobenzene near its consolute point using an optical method. In particular, the critical exponent beta describing the coexistence curve was measured for this system. Previous experimental values of beta for n-heptane+nitrobenzene were higher than the typical theoretically calculated value, an unusual, although not unique, occurrence. In an effort to study this discrepancy, we have used an improved experimental apparatus for our measurements. We have taken special care to minimize temperature gradients and maximize the temperature stability of our thermal control system. We have also exploited features of a known optical method to analyze, thoroughly, sources of systematic errors. We measured an apparent value of beta as 0.367+/- 0.006 and by a careful study of the known sources of error we find that they are not able to remove the discrepancy between the measured and the theoretical values of beta. We also measured the critical temperature of the system at Tc=291.80+/- 0.02 K (18.65 C).

cond-mat.dis-nn↗

arXiv2005

Lorentz-Lorenz Coefficient, Critical Point Constants, and Coexistence Curve of 1,1-Difluoroethylene

We report measurements of the Lorentz-Lorenz coefficient density dependence, the critical temperature, and the critical density, of the fluid 1,1-difluoroethylene. Lorentz-Lorenz coefficient data were obtained by measuring refractive index and density of the same fluid sample independently of one another. Accurate determination of the Lorentz-Lorenz coefficient is necessary for transformation of refractive index data into density data from optics-based experiments on critical phenomena of fluid systems done with different apparatus, with which independent measurement of the refractive indes and density is not possible. Measurements were made along the coexistence curve of the fluid and span the density range 0.01 to 0.80 g/cc. The Lorentz-Lorenz coefficient results show a stronger density dependence along the coexistence curve than previously observed in other fluids, with a monotonic decrease from a density of about 0.2 g/cc onwards, and an overall variation of about 2.5% in the density range studied. No anomaly in the Lorentz-Lorenz coefficient was observed near the critical density. The critical temperature is measured at Tc=(302.964+-0.002) K (29.814 C) and the measured critical density is (0.4195+-0.0018)g/cc.

cond-mat.dis-nn↗