Acta Phys. -Chim. Sin. ›› 2005, Vol. 21 ›› Issue (07): 813-816.doi: 10.3866/PKU.WHXB20050723

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Tricritical Phenomena in Quasi-ternary Solutions of Water+Formamide+Cyclohexane+Diethylene Glycol Monobutyl Ether

HOU Hai-yun; AN Xue-qin; SHEN Wei-guo   

  1. Department of Chemistry, Lanzhou University, Lanzhou 730000; College of Chemistry and Environment Science, Nanjing Normal University, Nanjing 210097; Department of Chemistry, East China University of Science and Technology, Shanghai 200237
  • Received:2004-11-30 Revised:2005-02-02 Published:2005-07-15
  • Contact: SHEN Wei-guo E-mail:shenwg@lzu.edu.cn

Abstract: The tricritical phenomena of quasi-ternary solutions of H2O+formamide(FA)+cyclohexane+diethylene glycol monobutyl ether have been studied by measurements of the volume ratios of the coexisting phases for a series of solutions with various overall compositions at various temperatures. Taking (H2O+FA) as a quasi “pure” component, the mass fraction FA in the quasi “pure” component controlled the approach to the tricritical point. As the mass fraction increased from 0 to 0.206, the ΔT of the three-phase region reduced from 1.500 ℃ to 0.228 ℃. By extrapolation of the experimental data, the tricritical mass fraction of FA in the quasi “pure” component and the tricritical temperature were obtained to be 0.286±0.003 and (54.8±0.69) ℃, respectively. It was found that the water-oil sides of three-phase triangles at the middle temperatures of the three-phase regions were almost parallel to the water-oil sides of the triangle coordinates. The dependences of lengths of the water-oil side of the three-phase triangle and the corresponding altitude to the water-oil side on ΔT were consistent with the classical theory.

Key words: Phase volume, Quasi-ternary system, Tricritical phenomena, Diethylene glycol monobutyl ether