The static dielectric constant of methyl chloride to 473 K and 200 MPa

1989

The static dielectric constant E of chlorodifluoromethane, CHC1F2, was measured between 233 and 368 K and from 0.5 to 200 MPa. (T, = 369 K). The high pressure capacitor cell and the procedure are described. At 233 K E increases from 9.84 to 12.19 with pressures from 0.5 to 200 MPa. At 298 K the increase reaches from 6.24 to 8.75 with pressures from 2.5 to 200 MPa. At 368 K and 200 MPa E = 6.70 is found. At the critical point c is equal to 2.35. Adjusted functions of E in dependence of temperature and pressure and of temperature and density are given. Tables and diagrams with data at round T and p-values as well as with data for liquid and gas along the coexistence curve are given. Kirkwood correlation factors between 1.0 and 1.20 were found.

Section: Introductionmentioning

confidence: 99%

The dielectric constant of chlorodifluoromethane to 200 MPa

Uematsu

1989

The Static Dielectric Constant of Methyl Cyanide to 350°C and 2000 bar

Hill

Rosenzweig

1990

The relative static dielectric constant ε of methyl cyanide was measured from 20 to 350°C, from 50 to 2250 bar and for the liquid along the saturation line to 270°C (Tc = 274.7°C). — Equipment and experimental procedure are described. At 20°C and pressures of 50 and 2000 bar ε changes from 37.7 to 42.9. At 100°C the change over the same pressure range is from 26.6 to 32.4 and at 300°C from 2.50 to 18.5. The accuracy of the data is ±0.4% up to 100°C and ±0.6% up to 300°C. Above 300°C and below 200 bar the data may be uncertain within ±1 or ±2%. Diagrams with ε‐values in dependence of density and temperature are given. The Kirkwood correlation factor below a density of 0.4 g cm−3 is slightly above unity. At densities higher than 0.4 g cm−3 ε declines at all temperatures to about 0.8 at 0.8 g cm−3. This may indicate a certain degree of dimerization, which is discussed.

The Static Dielectric Constant and Density of t‐Butyl Chloride to 200°C and 2000 bar

Vani

Michelberger

1990

The relative static dielectric constant or permittivity E and density e of t-butyl chloride was measured between 25 "C and 200°C and from 100 to 2000 bar. The high pressure cell, simultaneously applicable to determine E and e, is described. Sample densities range from 0.694 to 0.949 g.cm-'. At 25°C and from 100 to 600 bar E increases from 9.86 to 10.59. At 100°C between 100 and 2000 bar E ranges from 6.75 to 8.57. At 200°C from 200 to 2000 bar E grows from 4.12 to 5.69. Functions for E and e in dependence of pressure with fitted parameters are given. Calculated Kirkwood correlation factors g are presented, which exceed unity only moderately (from 1.03 to 1.22).A comparison is made with &-values of high pressure HCl and CH3Cl. IntroductionLiquids with polar molecules are good solvents, and the relative dielectric permittivity or dielectric constant is an important characteristic of such liquids. Knowledge of this property also contributes to the understanding of molecular interaction. The study of the dielectric constant over a wider range of temperature and pressure offers additional insight and may also open up new aspects for application. A comprehensive, satisfactory theoretical treatment of the dielectric behaviour of polar fluids which covers wide variations of molecular sizes, dipole moments, temperature, density and mixture conditions is not yet available. The classic state of the knowledge is reviewed and discussed by Bottcher [l].The dielectric constant of a number of fluids with small polar molecules has been studied experimentally in recent years in the supercritical range at high pressures. Among these fluids are NH3 [5], HCl [ 6 ] , CH3F [7], CHF3 [7], CH3Cl [S], CH30H [9], CHCIFz [lo], and CH2Cl2 [ll]. It was the aim of the present work to supplement the measurements with HCl [6] and CH3C1 [S] with the investigation of a fluid with molecules of similar structure but of larger size, namely tertiary butyl chloride, (CH3)3CCl. The dielectric constant values were to be combined with experimental density data. The region of temperatures and pressures should extend from 25 "C to 200°C and to 2000 bar. Earlier dielectric measurements with t-butyl chloride have been reported by Harris, Haycock and Alder [I23 and by Wilmers, Briese and Wurflinger [13]. The results of Harris et al. cover the range from 14°C to 50°C and pressures up to 200 bar. The work of Wilmers et al. was mainly concerned with the analysis of dielectric behaviour of the four different solid phases and the phase equilibria at temperatures below 40°C and at pressures up to 3000 bar. In the narrow range of overlap the agreement between the present results and those of Harris et al. and Wilmers et al. could be examined.