Observation of Liquid–Liquid Phase Transitions in Ethane at 300 K

Abstract

We have conducted Raman spectroscopy experiments on liquid ethane (C 2 H 6 ) at 300 K, obtaining a large amount of data at very high resolution. This has enabled the observation of Raman peaks expected but not previously observed in liquid ethane and a detailed experimental study of the liquid that was not previously possible. We have observed a transition between rigid and nonrigid liquid states in liquid ethane at ca. 250 MPa corresponding to the recently proposed Frenkel line, a dynamic transition between rigid liquid (liquidlike) and nonrigid liquid (gaslike) states beginning in the subcritical region and extending to arbitrarily high pressure and temperature. The observation of this transition in liquid (subcritical) ethane allows a clear differentiation to be made between the Frenkel line (beginning in the subcritical region at higher density than the boiling line) and the Widom lines (emanating from the critical point and not existing in the subcritical region). Furthermore, we observe a narrow transition at ca. 1000 MPa to a second rigid liquid state. We propose that this corresponds to a state in which orientational order must exist to achieve the expected density and can view the transition in analogy to the transition in the solid state away from the orientationally disordered phase I to the orientationally ordered phases II and III.

Raman spectroscopy of ethane (C2H6) to 120 GPa at 300 K

“…These are the ν 3 C‐C stretching mode, the ν 11 C‐H 3 deformation mode, the ν 1 C‐H totally symmetric stretching mode, and the ν 10 C‐H stretching mode [16]. We are using the nomenclature from our paper on liquid ethane [2]. Further details on the Raman mode assignment are provided in the supporting information.…”

“…A figure is provided in the supporting information comparing the fit in the solid state when the group is fitted with three and four components. Additionally, we have refitted our data from Proctor et al [2] collected close to crystallization in both the liquid and the solid states to illustrate the relation between the liquid and solid state peak assignments. This is also shown in a figure in the supporting information.…”

“…Relatively little is known about the behaviour of ethane (C 2 H 6 ) at high pressure. The fundamental equation of state (EOS) of the fluid states is backed by experimental data only to 0.07 GPa [1], and we recently published a detailed Raman study of the liquid state at 300 K up to crystallization at 2.5 GPa [2]. As far as the solid phases are concerned, there are two works available covering the pressure range up to ~8 GPa [3, 4], which are in disagreement.…”

Studi Termodinamika Transpor Ionik Natrium Klorida Dalam Air dan Campuran Tertentu

“…Massa Molar (137)(138)(139) Penampilan Densitas (140)(141)(142) Titik Lebur (143)(144)(145) Titik Didih (146)(147)(148) Kelarutan (149)(150)(151) Dalam Air (152)(153)(154) 58,44 g/mol Massa [222][223][224][225][226]…”

Kalium Dikromat (K2Cr2O7) Spektroskopi dan Transpor K2Cr2O7

“…Kalium dikromat (41) merupakan suatu unsur yang dalam padatan berwarna jingga, larut dalam air dan tidak menimbulkan bau (tak berbau). Larutan kalium dikromat (254) memilki pH 3,37 pada 100 g/L air, memiliki titik didih dan lebur sebesar >5000 0 C dan 3980 0 C, massa molar 294,19 g/mol dan densitas 2,69 g/cm 3 (44). Kalium dikromate (45) adalah oksidator kuat (255), secara teoritis oksidator ini dapat mengoksidasi senyawa organik sampai hampir sempurna (95-100%) .…”