SDS Volume (2)
Volume 20. Halogenated Benzenes, Toluenes and Phenols with Water, p 13
Original Measurements
Toyota, H.; Kuwahara, M.; Nippon Dojohiryogaku Zasshi 1967, 38(2,3), 93-97.
Variables:
Room Temp:
27
°C
Acidity:
5.0, 5.5, 6.0, 6.5, 7.0, 7.5, and 8.0
Amount concentration (2):
[NH4Cl] = 0.0 - 1.0 mol/dm3
mol/L
Prepared by:
Method/Apparatus/Procedure:
Pentachlorophenol and various amounts of $\ce{NaOH}$ and $\ce{NH4Cl}$ were dissolved in water at 27 °C and the solutions were left for three days with occasional stirring (once a day for one hour). Then, the undissolved pentachlorophenol was filtered off and the pH values of the filtrates were measured with a glass electrode. To each aliquot of the solutions was added hydrochloric acid to maintain their pH < 3. The precipitates which resulted were aged and weighed.
Source and Purity of Materials:
- Nothing specified.
- Nothing specified.
- Nothing specified.
Estimated Errors:
Mass concentration (m/v) (1): No estimation was given for errors in the solubility measurements. However, the reported values of S/S° (S the solubility of pentachlorophenol in KCI solutions and S° its solubility in pure water) do not fall on a single smooth curve, but rather spread. Therefore, the errors may be estimated to be larger than 2-3%.
Components:
- Pentachlorophenol, $\ce{ C6HCl5O }$; [87-86-5] NIST WebBook
- Ammonium chloride, $\ce{ NH4Cl }$; [12125-02-9] NIST WebBook
- Water, $\ce{ H2O }$; [7732-18-5] NIST WebBook
Experimental Data
Comments: Solubilities of pentachlorophenol in water versus hydrogen ion activity, in the absence of $\ce{KCl}$, at $\pu{27^{\circ}C}$ were measured and calculated. The stoichiometric amounts of dissolved pentachlorophenol were calculated from mass balance based upon incomplete dissociation. The dissociation constant was given as $K_{p} =[\ce{C6Cl5O^{-}}] [\ce{H^{+}}]/[\ce{C6Cl5OH}] = \pu{3.2E-5 mol/L}$. This value together with the activity of the hydrogen ion, {$\ce{H^{+}}$}, as determined from pH measurements was incorporated in an equation for calculating the solubility: $$S = [\pu{1.796E-6}/{\ce{H^{+}}}0.170] [1 + \pu{3.2E-5}/{\ce{H^{+}}}]$$ Observed and calculated values reported:
| 105 mol (1)/L | 104 mol (1)/L | 103 mol (1)/L | |
|---|---|---|---|
| pH | 5.0 | 6.0 | 7.0 |
| Observed value: | 4.05 | 6.05 | 8.85 |
| Calculated value: | 5.34 | 6.20 | 8.90 |
| $T$ (°C) | pH | $x_{1}$ | $C_{1}$ (mol/dm3) | $C_{2}$ (mol/dm3) |
|---|---|---|---|---|
| 27 | 8 | 2.223 x 10-5 | 1.23 x 10-3 | 1.0 |
| 27 | 8 | 3.920 x 10-5 | 2.17 x 10-3 | 0.50 |
| 27 | 8 | 4.299 x 10-5 | 2.38 x 10-3 | 0.30 |
| 27 | 8 | 8.458 x 10-5 | 4.68 x 10-3 | 0.20 |
| 27 | 8 | 1.257 x 10-4 | 6.95 x 10-3 | 0.10 |
| 27 | 8 | 1.973 x 10-4 | 0.0109 | 0.05 |
| 27 | 8 | 1.338 x 10-3 | 0.0728 | 0.0 |
(a) Calculated by F. W. Getzen.
(b) Reported.
(c) Calculated mole fraction based upon complete dissociation of NH4Cl.
(d) pH value of solution equilibriated with precipitate.
