IUPAC-NIST Solubilities Database

IUPAC-NIST Solubility Database
NIST Standard Reference Database 106

Solubility System: Octane with Water

Components:
   (1) Water; H2O; [7732-18-5]  NIST Chemistry WebBook for detail
   (2) Octane; C8H18; [111-65-9]  NIST Chemistry WebBook for detail

Original Measurements:
   Heidman, J.L.; Tsonopoulos, C.; Brady, C.J.; Wilson, G.M., A. I. Ch. E. J. 1985, 31, 376-84.

Variables:
   Temperature = 311 K - 553 K
   Pressure = 0.01-7.4 MPa

Prepared By:
   G.T. Hefter

Experimental Remarks:

   The three phase critical point was reported to be 539.1 ± 0.6 K, 7.37 ± 0.04 MPa and x₁ = 4.61 × 10^-4 (0.292 g(1)/100 g sln, compiler).

The authors also report an equation which fit their own and literature data over the range 273-539 K, viz.

ln x₁ = -343.1497 + 13862.49/T + 49.24609 ln T

ln x₂ = -0.66037 - 7.1130 (T_r^-1 - 1) - 0.67885 (1 - T_r)^1/3 - 1.43381 (1 - T_r)
where T_r = T/539.1

Experimental Data: (Notes on the Nomenclature)

Solubility of octane in water
T/K	Pressure [Mpa]	10² * g₁/100 g solution (compiler)	10⁵ * Mole Fraction x₁
310.9	0.0103^a	0.0076	0.012
366.5	0.117^a	0.030	0.048
422.0	0.655	0.24	0.38
479.5	2.51	2.5	4.0
536.1	7.03	22	35
552.8	8.86	38	60^b

Solubility of water in octane
T/K	Pressure [Mpa]	g₂/100 g solution (compiler)	10² * Mole Fraction x₂
310.9	0.0103^a	0.0158	0.100
366.5	0.117	0.098	0.62
422.0	0.655	0.622	3.94
477.6	-^b	2.22	12.6
533.1	-^b	9.05	38.7
539.1 (c)	7.41	14.9	52.7^c
550.4 (d)	-	16.1	54.9^d

Notes:
   Table 1  ^a  Estimated by the authors from pure component data.
   Table 1  ^b  Above three-phase equilibrium point.
   Table 2  ^a  Estimated by the authors from pure component data.
   Table 2  ^b  Not specified.
   Table 2  ^c  Three phase critical point.
   Table 2  ^d  Above three phase critical point.

Method/Apparatus/Procedure:
   Experimental procedure was similar to that used in ref. 1. Hydrocarbons were determined by gas chromatography and water by Karl Fischer titration. Critical points were determined by the synthetic method using visual observation. This aspect of the procedure is discussed in detail in the paper.

Source and Purity of Materials:
   (1) Aldrich 99+ mol %; water free purity greater than or equal to 99.9 mol %, checked by gas chromatography.
   (2) Distilled; no details given.

Estimated Errors:
   Solubility: ± 5%, relative precision of replicate analyses.
   Temperature: not stated.
   Pressure: ± 1%; type of error not stated.

References:
   ¹Tsonopoulos, C.; Wilson, G.M., A. I. Ch. E. J. 1983, 29, 990-9.