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IUPAC-NIST Solubility Database
NIST Standard Reference Database 106
Solubility System:
2-Propanol with Heptane and Water
Components:
(1) Water; H2O; [7732-18-5]
NIST Chemistry WebBook
for detail
(2) 2-Propanol (isopropanol, isopropyl alcohol); C3H8O; [67-63-0]
NIST Chemistry WebBook
for detail
(3) Heptane (n-heptane); C7H16; [142-82-5]
NIST Chemistry WebBook
for detail
Evaluator:
A. Skrzecz, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland (1996.05)
Critical Evaluation:
A survey of reported compositions along the saturation curve (sat), and compositions of coexisting phases in equilibrium (eq.) for the system 2-propanol-heptane-water is given in Table 64.
Saturation curve
The ternary system 2-propanol-heptane-water forms a large miscibility gap of type 1 covering the majority of the concentration triangle. Only the heptane-water binary system forms a miscibility gap. The data of this binary system were compiled and critically evaluated in a previously published SDS volume.
3
The recommended mutual solubilities of the binary system heptane-water at 298.2 are
x
"
2
=4.3·10
–7
and
x
'
3
=5.6·10
–4
. Solubility of water in heptane
x
'
3
=5.5·10
–3
, reported by Vorobeva and Karapetyants
1
is 10 times higher but it is consistent with the accuracy of experiments –0.001 mass fraction. A heptane free point on the saturation curve
x
1
=0.049) in the data of Letcher
et al
.
2
ought to be treated as an artifact of the experimental accuracy. The data are not sufficiently accurate to describe the regions of low concentration of 2-propanol. All compositions of coexisting phases in equilibrium in both data sets are consistent with independently measured saturation curve and with one another. The data of Letcher
et al
. Ref. 2, show slightly larger solubility for the heptane-poor phase in the region of
x
2
=0.2–0.4. The maximum of 2-propanol concentration is observed on saturation curve which at 298.2 K reaches
x
1
=0.46±0.01 and
x
2
=0.18±0.02 mole fraction. All experimental solubility and equilibrium data reported at 298.2 K were used for calculation of saturation curve. (Water-rich and hydrocarbon-rich branches were treated together.) These data were described by the equation:
x
1
=0.651 25+0.083 32 ln(
x
2
)–0.261 69
x
2
–0.404 01
x
2
2
.
The least-squares method was used and the standard error of estimate was 0.0186. The equation describes the saturation curve for <0.91 mole fraction. The compositions on the saturation curve, calculated by the proposed equation are presented in Table 65 for
x
2
selected concentrations of heptane in the mixture and in
Figure 33
as calculated binodal curve (solid line).
Phases in equilibrium
Compositions of coexisting phases in equilibrium for the ternary system 2-propanol-heptane-water were reported in both references at the same temperature 298 K. A plait point of liquid-liquid equilibrium obtained graphically by Vorobeva and Karapetyants
1
was
x
1
=0.440 and
x
2
=0.279. The tie lines of Ref. 1 cover the whole range of miscibility gap, while only three tie lines of Ref. 2 cover the middle region of miscibility gap 0.1<
x
1
<0.27. The compositions of phases in equilibrium reported in Refs. 1 and 2 are consistent. The system behavior, calculated saturation curve as well as the experimental data are presented in
Figure 33
.
Experimental Data:
(Notes on the Nomenclature)
TABLE 64. Summary of experimental data for the system 2-propanol-heptane-water
Author
T/K
DataType
Reference
Vorobeva and Karapetyants, 1967
298
sat. (14), eq. (10)
1
Letcher
et al
., 1986
298
sat. (8), eq. (3)
2
TABLE 65. Calculated compositions along the saturation curve at 298.2
T/K
Mole Fraction x
1
Mole Fraction x
2
298.2
0.0000
4.3 Ref. 6
298.2
0.0754
0.0010
298.2
0.2649
0.0100
298.2
0.3199
0.0200
298.2
0.3719
0.0400
298.2
0.3997
0.0600
298.2
0.4173
0.0800
298.2
0.4292
0.1000
298.2
0.4374
0.1200
298.2
0.4429
0.1400
298.2
0.4463
0.1600
298.2
0.4482
0.1800
298.2
0.4487
0.2000
298.2
0.4480
0.2200
298.2
0.4463
0.2400
298.2
0.4437
0.2600
298.2
0.4402
0.2800
298.2
0.4361
0.3000
298.2
0.4312
0.3200
298.2
0.4257
0.3400
298.2
0.4196
0.3600
298.2
0.4128
0.3800
298.2
0.4056
0.4000
298.2
0.3978
0.4200
298.2
0.3895
0.4400
298.2
0.3807
0.4600
298.2
0.3714
0.4800
298.2
0.3616
0.5000
298.2
0.3514
0.5200
298.2
0.3408
0.5400
298.2
0.3297
0.5600
298.2
0.3182
0.5800
298.2
0.3062
0.6000
298.2
0.2939
0.6200
298.2
0.2811
0.6400
298.2
0.2679
0.6600
298.2
0.2544
0.6800
298.2
0.2404
0.7000
298.2
0.2260
0.7200
298.2
0.2113
0.7400
298.2
0.1961
0.7600
298.2
0.1806
0.7800
298.2
0.1647
0.8000
298.2
0.1485
0.8200
298.2
0.1318
0.8400
298.2
0.1148
0.8600
298.2
0.0974
0.8800
298.2
0.0797
0.9000
298.2
0.0000
0.999 44 Ref. 6
View Figure 1 for this Evaluation
Notes:
Table 64
Number of experimental points in parentheses.
References: (Click a link to see its experimental data associated with the reference)
1
Vorobeva, A.I.; Karapetyants, M., Kh., Zh. Fiz. Khim. 41, 1984-9 (1967).
2
Letcher, T.M.; Wootton, S.; Shuttleworth, B.; Heyward, C., J. Chem. Thermodyn 18, 1037 (1986).
3 Shaw, D.G., ed., Solubility Data Series, Vol. 37, Hydrocarbons with Water and Seawater, Part I: Hydrocarbons C5 to C7 (Pergamon, New York, 1989).