TY - JOUR
T1 - Prediction of the vapor-liquid distribution constants for volatile nonelectrolytes in water up to its critical temperature
AU - Plyasunov, Andrey V.
AU - Shock, Everett
N1 - Funding Information:
It is our pleasure to make this contribution for the special volume to honor Robert Walker. The fate of volatile elements and compounds throughout the solar system has been a theme of his research for many years. We hope there are sufficient fundamentals of physical interactions to satisfy his sense for rigor, and applications that are broad enough to fuel his imagination. One of us (ELS) wishes to thank Bob for many helpful, constructive, challenging and sustaining conversations. The authors are grateful to Natalia Plyasunova for pointing out problems in an earlier version of the group contribution method and to Robert H. Wood for continuing cooperation and consultations. This work has benefited greatly from thorough comments and constructive suggestions of Dennis K. Bird and two anonymous reviewers. The careful editing and reconciliation of difference of opinions by GCA Associate Editor David J. Wesolowski is much appreciated. This research was supported by US Department of Energy (DOE) grant number DE-FG02–92ER-14297.
PY - 2003/12/15
Y1 - 2003/12/15
N2 - The distribution of solutes between coexisting liquid and vapor phases of water can be expressed by the distribution constant, KD, defined as KD=lim y/x, x→0 where y and x stand for the mole fraction concentrations of a solute in vapor and liquid phases, respectively. Research reported here is concerned with the prediction of this property, KD, for volatile nonelectrolytes, over the whole temperature range of existence of the vapor-liquid equilibrium for water, i.e. from 273 K to the critical temperature at 647.1 K. A simple empirical method is proposed to extrapolate the values of KD from 298 K to 500-550 K. Calculations at higher temperatures are based on the theoretical relation that establishes the proportionality between RTlnKD and the Krichevskii parameter, AKr, which is the single most important property of a solute at near-critical conditions, and can be evaluated using the method proposed here. The comparison of predicted and experimental values of KD and AKr for a few well-studied solutes reveals the satisfactory performance of the proposed method. It appears that the accuracy of predictions in the framework of this method is limited mainly by the accuracy of the values of the thermodynamic functions of hydration of solutes at 298 K, and that the best way to improve the quality of predictions of KD and AKr is to increase the inventory of accurate calorimetric enthalpy and heat capacity data for aqueous solutes at 298 K. We stress that the values of the Krichevskii parameter, such as those generated in this study, are of crucial importance for reliable predictions of the chemical potential and its derivatives (V2o, Cp2o) for aqueous solutes at near-critical and supercritical conditions. Values of KD and AKr are predicted for many inorganic volatile nonelectrolytes and some halogenated derivatives of methane and ethene. We show that both ln KD and AKr for aqueous organic solutes follow group additivity systematics, and we derive a set of corresponding group contribution values for several functional groups (material point, CH3, CH2, CH, C, C = C, HC = CH, C≡C, HCar, Car, Cfus, OH, O, S, SH, CO, COO, COH, COOH, CN, F, Cl, Br, NH2, NH, N, etc.).
AB - The distribution of solutes between coexisting liquid and vapor phases of water can be expressed by the distribution constant, KD, defined as KD=lim y/x, x→0 where y and x stand for the mole fraction concentrations of a solute in vapor and liquid phases, respectively. Research reported here is concerned with the prediction of this property, KD, for volatile nonelectrolytes, over the whole temperature range of existence of the vapor-liquid equilibrium for water, i.e. from 273 K to the critical temperature at 647.1 K. A simple empirical method is proposed to extrapolate the values of KD from 298 K to 500-550 K. Calculations at higher temperatures are based on the theoretical relation that establishes the proportionality between RTlnKD and the Krichevskii parameter, AKr, which is the single most important property of a solute at near-critical conditions, and can be evaluated using the method proposed here. The comparison of predicted and experimental values of KD and AKr for a few well-studied solutes reveals the satisfactory performance of the proposed method. It appears that the accuracy of predictions in the framework of this method is limited mainly by the accuracy of the values of the thermodynamic functions of hydration of solutes at 298 K, and that the best way to improve the quality of predictions of KD and AKr is to increase the inventory of accurate calorimetric enthalpy and heat capacity data for aqueous solutes at 298 K. We stress that the values of the Krichevskii parameter, such as those generated in this study, are of crucial importance for reliable predictions of the chemical potential and its derivatives (V2o, Cp2o) for aqueous solutes at near-critical and supercritical conditions. Values of KD and AKr are predicted for many inorganic volatile nonelectrolytes and some halogenated derivatives of methane and ethene. We show that both ln KD and AKr for aqueous organic solutes follow group additivity systematics, and we derive a set of corresponding group contribution values for several functional groups (material point, CH3, CH2, CH, C, C = C, HC = CH, C≡C, HCar, Car, Cfus, OH, O, S, SH, CO, COO, COH, COOH, CN, F, Cl, Br, NH2, NH, N, etc.).
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U2 - 10.1016/j.gca.2003.08.003
DO - 10.1016/j.gca.2003.08.003
M3 - Article
AN - SCOPUS:0345801350
SN - 0016-7037
VL - 67
SP - 4981
EP - 5009
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
IS - 24
ER -