Critical Constants of Inorganic Compounds The parameters of the liquid-gas critical point are important constants in determining the behavior of fluids. This table lists the critical temperature, pressure, and molar volume, as well as the normal boiling point, for over 140 inorganic substances. The properties and their units are: Tb : Normal boiling point in K at a pressure of 101.325 kPa (1 atmosphere); an “s” following the value indicates a sublimation point (temperature at which the solid is in equilibrium with the gas at a pressure of 101.325 kPa) Tc : Critical temperature in K Pc : Critical pressure in MPa Vc : Critical molar volume in cm3 mol–1 The number of digits given for Tb , Tc , and Pc indicates the estimated accuracy of these quantities; however, values of Tc greater than 750 K may be in error by 10 K or more. Although most Vc values are given to three figures, they cannot be assumed accurate to better than a few percent. All values are experimentally determined except for a few values, indicated by an asterisk*, that are based on extrapolations. Methods of measurement are described and critiqued in Reference 1. Compounds are listed alphabetically by name. References 1. Ambrose, D., and Young, C. L., J. Chem. Eng. Data 40, 345, 1995. 2. Morel, V., Bultel, A., and Chéron, B. G., Int. J. Thermophys. 30, 1853, 2009. 3. Ambrose, D., “Vapor-Liquid Constants of Fluids,” in Handbook of the Thermodynamics of Organic Compounds, Stevenson, R. M., and Malanowski, S., Eds., Elsevier, New York, 1987. 4. Sato, M., Masui, G., and Uematsu, M., J. Chem. Thermodyn. 37, 931, 2005. 5. Velasco, S., Roman, F. L., White, J. A., and Mulero, A., Fluid Phase Equilib. 244, 11, 2006. 6. Nowak, P., Tielkes, T., Kleinrahm, R., and Wagner, W., J. Chem. Thermodyn. 29, 885, 1997. 7. Lemmon, E. W., and Span, R., J. Chem. Eng. Data 51, 785, 2006. 8. Goodwin, R. D., J. Phys. Chem. Ref. Data 14, 849, 1985. 9. Vargaftik, N. B., Int. J. Thermophys. 11, 467, 1990. 10. Nikitin, E. D., Pavlov, P. A., Popov, A. P., and Nikitina, H. E., J. Chem. Thermodyn. 27, 945, 1995. 11. Dillon, I. G., Nelson, P. A., and Swanson, B. S., J. Chem. Phys. 44, 4229, 1966. 12. Huber, M. L., Laesecke, A., and Friend, D. G., The Vapor Pressure of Mercury, NISTIR 6643, National Institute of Standards and Technology, Boulder, CO, March 2006; Ind. Eng. Chem. Res. 45, 7351, 2006. 13. Rau, H., Kutty, T. R. N., and Guedes de Carvalho, J. R. F., J. Chem. Thermodyn. 5, 291, 1973. 14. Funke, M., Kleinrahm, R., and Wagner, W., J. Chem. Thermodyn. 34, 717, 2002. 15. Sifner, O., and Klomfar, J., J. Phys. Chem. Ref. Data 23, 63, 1994. Name Formula Tb /K Tc /K Pc /MPa Vc /cm3 mol–1 Ref. Aluminum Al 2792 6700* 2 Aluminum bromide AlBr3 528 763 2.89 310 3 Aluminum chloride AlCl3 453 s 620 2.63 257 3 Aluminum iodide AlI3 655 983 408 3 Ammonia NH3 239.82 405.56 11.357 69.8 3,4 Ammonium chloride NH4 Cl 611 s 1155 163.5 3 Antimony(III) bromide SbBr3 561 904 300 3 Antimony(III) chloride SbCl3 493.5 794 272 3 Antimony(III) iodide SbI3 673 1102 3 Argon Ar 87.302 150.687 4.863 75 3 Arsenic As 889 s 1673 22.3 35 3 Arsenic(III) chloride AsCl3 403 654 252 3 Arsine AsH3 210.7 373.1 3 Beryllium Be 2741 5205* 5 Bismuth Bi 1837 4620* 5 Bismuth tribromide BiBr3 735 1220 301 3 Bismuth trichloride BiCl3 714 1179 12.0 261 3 Boron tribromide BBr3 364.4 581 272 3 Boron trichloride BCl3 285.80 455 3.87 239 3 Boron trifluoride BF3 173.3 260.8 4.98 115 3 Boron triiodide BI3 482.7 773 356 3 Bromine Br2 332.0 588 10.34 127 3 Carbon dioxide CO2 194.6 s 304.13 7.375 94 6 Carbon disulfide CS2 319 552 7.90 173 3 Carbon monoxide CO 81.7 132.86 3.494 93 3,7,8 Carbon oxysulfide COS 223 375 5.88 137 3,7 Cesium Cs 944 1938 9.4 341 9 Chlorine Cl2 239.11 417.0 7.991 123 3 Chlorine pentafluoride ClF5 260.1 416 5.27 233 3 6-83 Name Formula Tb /K Tc /K Pc /MPa Vc /cm3 mol–1 Ref. Chlorotrifluorosilane SiClF3 203.2 307.7 3.46 3 Diborane B2 H6 180.8 289.8 4.05 3 Dichlorodifluorosilane SiCl2 F2 241 369.0 3.5 3 Difluoramine NHF2 250 403 3 cis-Difluorodiazine N2 F2 167.40 272 7.09 3 trans-Difluorodiazine N2 F2 161.70 260 5.57 3 Fluorine F2 85.04 144.41 5.1724 66 3 Fluorine monoxide F2 O 128.8 215 3 Gallium(III) bromide GaBr3 552 806.7 303 3 Gallium(III) chloride GaCl3 474 694 263 3 Gallium(III) iodide GaI3 613 951 395 3 Germane GeH4 185.1 312.2 4.95 147 3 Germanium Ge 3106 9802* 5 Germanium(IV) bromide GeBr4 459.50 718 392 3 Germanium(IV) chloride GeCl4 359.70 553.2 3.861 330 3 Germanium(IV) iodide GeI4 621 973 500 3 Hafnium(IV) bromide HfBr4 596 s 746 415 3 Hafnium(IV) chloride HfCl4 590 s 725.7 5.42 314 3 Hafnium(IV) iodide HfI4 667 s 916 528 3 Helium He 4.222 5.1953 0.22746 57 3 Hydrazine N2 H4 386.70 653 14.7 3 Hydrogen H2 20.388 33.14 1.2964 65 3 Hydrogen bromide HBr 206.77 363.2 8.55 3 Hydrogen chloride HCl 188 324.7 8.31 81 3 Hydrogen fluoride HF 293 461 6.48 69 3 Hydrogen iodide HI 237.60 424.0 8.31 3 Hydrogen peroxide H2 O2 423.4 728* 22* 10 Hydrogen selenide H2 Se 231.90 411 8.92 3 Hydrogen sulfide H2 S 213.60 373.1 9.00 99 3,7 Iodine I2 457.6 819 155 3 Iodine bromide IBr 389 719 139 3 Iron Fe 3134 9340* 5 Krypton Kr 119.735 209.48 5.525 91 3,7 Lithium Li 1615 3223* 67* 66* 11 Manganese Mn 2334 4325* 5 Mercury Hg 629.769 1764 167 43 3,12 Mercury(II) bromide HgBr2 591 1012 3 Mercury(II) chloride HgCl2 577 973 174 3 Mercury(II) iodide HgI2 624 1072 3 Molybdenum(V) chloride MoCl5 541 850 369 3 Molybdenum(VI) fluoride MoF6 307.2 473 4.75 226 3 Neon Ne 27.097 44.49 2.6786 42 3 Niobium(V) chloride NbCl5 520.6 803.5 4.88 397 3 Niobium(V) fluoride NbF5 507 737 6.28 155 3 Nitric oxide NO 121.41 180 6.48 58 3 Nitrogen N2 77.355 126.192 3.39 90 3 Nitrogen chloride difluoride NClF2 206 337.5 5.15 3 Nitrogen tetroxide N2 O4 294.30 431 10.1 167 3 Nitrogen trifluoride NF3 144.40 234.0 4.46 126 3 Nitrosyl chloride NOCl 267.7 440 3 Nitrous oxide N2 O 184.67 309.52 7.245 97 3,7 Nitryl fluoride NO2 F 200.8 349.5 3 Osmium(VIII) oxide OsO4 404.4 678 3 Oxygen O2 90.188 154.581 5.043 73 3 Ozone O3 161.80 261.1 5.57 89 3 Perchloryl fluoride ClO3 F 226.40 368.4 5.37 161 3 Phosphine PH3 185.40 324.5 6.54 3 Phosphonium chloride PH4 Cl 246 s 322.3 7.37 3 Phosphorothioc chloride difluoride PSClF2 279.5 439.2 4.14 3 Phosphorothioc trifluoride PSF3 220.90 346.0 3.82 3 6-84 Critical Constants of Inorganic Compounds Name Formula Tb /K Tc /K Pc /MPa Vc /cm3 mol–1 Ref. Phosphorus P 553.7 994 3 Phosphorus(III) bromide PBr3 446.4 711 300 3 Phosphorus(III) chloride PCl3 349.3 563 264 3 Phosphorus(V) chloride PCl5 433 s 646 3 Phosphorus(III) chloride difluoride PClF2 225.9 362.4 4.52 3 Phosphorus(III) dichloride fluoride PCl2 F 287.00 463.0 4.96 3 Phosphorus(III) fluoride PF3 171.4 271.2 4.33 3 Potassium K 1032 2223* 16* 209* 11 Radon Rn 211.5 377 6.28 3 Rhenium(VII) oxide Re2 O7 633 942 334 3 Rhenium(VI) oxytetrachloride ReOCl4 496 781 362 3 Rubidium Rb 961 2093* 16* 247* 11 Selenium Se 958 1766 27.2 3 Selenium hexafluoride SeF6 226.55 s 345.5 3 Selenium oxychloride SeOCl2 450 730 7.09 235 3 Silver Ag 2435 6410* 5 Sodium Na 1156 2573* 35* 116* 11 Sulfur S 717.76 1314 20.7 57.0 3,13 Sulfur chloride pentafluoride SF5 Cl 254.10 390.9 3 Sulfur dioxide SO2 263.10 430.64 7.884 122 3,7 Sulfur hexafluoride SF6 209.35 s 318.723 3.77 197 3,14 Sulfur tetrafluoride SF4 232.70 364 3 Sulfur trioxide SO3 317.7 491.0 8.2 127 3 Tantalum(V) bromide TaBr5 622 974 461 3 Tantalum(V) chloride TaCl5 512 767 402 3 Tellurium Te 1261 2329* 5 Tellurium hexafluoride TeF6 234.25 s 356 3 Tellurium tetrachloride TeCl4 660 1002 8.56 310 3 Tetrabromosilane SiBr4 427 663 382 3 Tetrachlorosilane SiCl4 330.80 508.1 3.593 326 3 Tetrafluorohydrazine N2 F4 199 309 3.75 3 Tetrafluorosilane SiF4 187 259.0 3.72 3 Tetraiodosilane SiI4 560.50 944 558 3 Tin(IV) bromide SnBr4 478 744 417 3 Tin(IV) chloride SnCl4 387.30 591.9 3.75 351 3 Tin(IV) iodide SnI4 637.50 968 531 3 Titanium(IV) bromide TiBr4 506.7 795.7 391 3 Titanium(IV) chloride TiCl4 409.60 638 4.66 339 3 Titanium(IV) iodide TiI4 650 1040 505 3 Tribromosilane SiHBr3 382 610.0 305 3 Trichlorofluorosilane SiCl3 F 285.40 438.6 3.58 3 Trichlorosilane SiHCl3 306 479 268 3 Trifluoramine oxide NOF3 185.7 303 6.43 147 3 Tungsten(VI) chloride WCl6 610 923 422 3 Tungsten(VI) fluoride WF6 290.3 444 4.34 233 3 Tungsten(VI) oxytetrachloride WOCl4 503 782 338 3 Uranium(VI) fluoride UF6 329.65 s 505.8 4.66 250 3 Vanadyl chloride VOCl 400 636 171 3 Water H2 O 373.12 647.10 22.06 56 3 Xenon Xe 165.051 289.733 5.842 118 7,15 Xenon difluoride XeF2 387.50 s 631 9.32 148 3 Xenon tetrafluoride XeF4 388.90 s 612 7.04 188 3 Zirconium(IV) bromide ZrBr4 633 s 805 424 3 Zirconium(IV) chloride ZrCl4 604 s 778 5.77 319 3 Zirconium(IV) iodide ZrI4 704 s 960 530 3 Critical Constants of Inorganic Compounds 6-85