The trichlorofluoromethane (1) and water (2)
binary system is discussed in two parts; part 1 is trichlorofluoromethane (1)
in water (2) and part 2 is water (2) in trichlorofluoromethane (1).
Part 1. The solubility of trichlorofluoromethane (1) in water (2) has
been studied by at least eleven different work groups with only partial agreement
of results. The data of Howe et al. (ref. 1) are substantially lower
than other measurements and are therefore rejected. The solubility data reported
by du Pont (refs. 2 and 3), Rauws et al. (ref. 4), McConnell et al.
(ref. 5), Pearson and McConnell (ref. 6), and Sukornick (ref. 7) show some consistency,
while the measurements reported by Park et al. (ref. 8), Warner and Weiss
(ref. 9), Wisegarver and Cline (ref. 10), Warner et al. (ref. 11), Balls
(ref. 14), and Zeininger (ref. 15) are relatively high in value.
It may be assumed that the solubility data reported in the du Pont bulletins
were produced in the same laboratories with similar methods and accuracy at
298.15 and 304.15 K, respectively. There appears to be no significant difference
between the two data points despite the 6 K difference in temperature. Similarly,
the two measurements reported by McConnell et al. and Pearson and McConnell
in 1975 most likely were made in the same laboratories under much the same conditions.
There is no obvious reason to explain the difference between the lower (refs.
2, 3, 5, 6, and 7) and higher (refs. 8, 9, 10, 11, 14, and 15) sets of data.
In the opinion of the evaluator, there is not enough evidence to justify rejection
of measurements from either of the two data sets. Although both data sets are
classified as tentative, the smoothed solubility values in mass per cent (1) for the 273 through
313 K temperature interval (Table 1) are based upon a regression equation for
all data shown in Figure 1:
Solubility [100 w1] = 25.0094 – 0.16263 (T/K) + 2.6547 × 10–4 (T/K)2
with a standard error of 5.0 × 10–2 about
the regression line.
A minimum solubility occurs for most halogenated hydrocarbons in water systems
between 270 and 310 K (refs. 12 and 13). A minimum solubility temperature can
be calculated from an enthalpy of solution at infinite dilution and a change
in solute heat capacity in going from a pure liquid to an infinitely dilute
aqueous solution. However, such thermodynamic data are rarely available in the
literature.
Part 2. The solubility of water (2) in trichlorofluoromethane (1) has
been measured by three research groups (refs. 2, 3, and 7) with only partially
consistent results with the exception of the measurements of Sukornick (ref.
7). Generally, the solubility behavior of water in halogenated hydrocarbons
shows a definite increase with increasing temperature. This trend has been demonstrated
in a comprehensive compilation of solubility data (ref. 12). The two measurements
at 294.15 and 298.15 K from the du Pont laboratories compare favorably with
the recommended values, whereas the reported value of Sukornick (ref. 7) at
304.15 K is low and classified as doubtful. More accurate solubility measurements
are required for more reliable values.