The atomic structural parameter P-i = (Z(i)*/n(i)*) (1 + n(i)*/n(i)) (1 + m(i)/Z) and the molecular structural parameter [GRAPHICS] are defined. The standard formation enthalpies (Delta(f)H(m)(phi)) of 74 species of r...The atomic structural parameter P-i = (Z(i)*/n(i)*) (1 + n(i)*/n(i)) (1 + m(i)/Z) and the molecular structural parameter [GRAPHICS] are defined. The standard formation enthalpies (Delta(f)H(m)(phi)) of 74 species of rare earth compounds were studied with P, and the correlation coefficient is R > 0.94. The structural factors and the properties of rare earth compounds are influenced by the Z(i)*, n(i)*, n(i), m(i), Z. This study has special referential value to predict the properties of rare earth compounds.展开更多
The topological index F* is defined and obtained by the method of a non-dimensional unit calculation in which three matrices multiply with each other. These matrices represent the connective cases of atoms in a molecu...The topological index F* is defined and obtained by the method of a non-dimensional unit calculation in which three matrices multiply with each other. These matrices represent the connective cases of atoms in a molecule, the structural features of atoms on top and the bonded cases of the adjacent atoms respectively. The standard formation enthalpies of ABn(g) molecules were correlated with F’* (A = C, Al, Si, Ti, Zr, B = F, Cl, Br, I, H, n=1 -4) and these correlation coefficients are all more than 0.96. Some molecules (e.g CH4, SiH4,etc. )can be preferably handled by F* but can not be dealt with by other topological indices. By contrast to traditional hydrogen suppressed graph, the contribution of hydrogen atoms to structures and properties of molecules is considered.展开更多
Balance solubility products and enthalpy of for- mation for NbC0.75, NbC0.85, NbC0.88, NbC and NbN in oriented silicon steels were calculated and compared quali- tatively. Meanwhile, the mixing enthalpies of these fiv...Balance solubility products and enthalpy of for- mation for NbC0.75, NbC0.85, NbC0.88, NbC and NbN in oriented silicon steels were calculated and compared quali- tatively. Meanwhile, the mixing enthalpies of these five Nb compounds were calculated based on Miedema Model. The results show that the solubility products of Nb compounds in ferrite and austenite meet the following relationship, NbC0.75 〉 NbC0.85 〉 NbC0.88 〉 NbC 〉 NbN and NbN has the minimum enthalpy of formation. It indicates that NbN easily precipitate out, but it is more difficult for NbC0.75.展开更多
The mixing enthalpies of 23 binary liquid alloys are calculated by molecular interaction volume model (MIVM), which is a two-parameter model with the partial molar infinite dilute mixing enthalpies. The predicted va...The mixing enthalpies of 23 binary liquid alloys are calculated by molecular interaction volume model (MIVM), which is a two-parameter model with the partial molar infinite dilute mixing enthalpies. The predicted values are in agreement with the experimental data and then indicate that the model is reliable and convenient.展开更多
The enthalpies of solution in water of complexes of RE(NO 3) 3 (RE=La~Nd, Sm~Lu, Y) with L α Histidine (His) were measured at 298.15 K. The standard enthalpies of formation of RE(His) 3+ (aq) were calculate...The enthalpies of solution in water of complexes of RE(NO 3) 3 (RE=La~Nd, Sm~Lu, Y) with L α Histidine (His) were measured at 298.15 K. The standard enthalpies of formation of RE(His) 3+ (aq) were calculated. The 'tetrad effect' regularity was observed from the curve, which is the enthalpies of solution plotted against the atomic numbers of the elements in lanthanide series.展开更多
'White powdery tungstic acid' has been used for preparing various types of tungsten-containing compounds due to its high reactivity. The present paper covers the standard molar enthalpies of formation, △H0/f ...'White powdery tungstic acid' has been used for preparing various types of tungsten-containing compounds due to its high reactivity. The present paper covers the standard molar enthalpies of formation, △H0/f of three tungsten- containing acids. The values found for 'white powdery tungstic acid' WO3·1. 68H2O, 'yellow tungstic acid' WO3·1. 20H2O and dodecatungstophosphoric acid H3(PW12O40)·25H2O at 298. 15 K were-(1312±1), - (1192±1) and -(18150±13) kJ mol-1, respectively.展开更多
Excess molar enthalpies,H^E,for the binary mixtures of 2-pentanol with n-alkanes(n-heptane,n-octane,and nnonane)have been determined at three different temperatures T=(293.15,298.15 and 303.15)K and normal atmospheric...Excess molar enthalpies,H^E,for the binary mixtures of 2-pentanol with n-alkanes(n-heptane,n-octane,and nnonane)have been determined at three different temperatures T=(293.15,298.15 and 303.15)K and normal atmospheric pressure over the entire composition range using a Calvet microcalorimeter.All mixtures show endothermic mixing with the maximum values of the excess enthalpies occurring in the n-alkane-rich region.The H^Edata are smoothed using Redlich–Kister equation.The applicability of the Treszczanowicz–Benson,ERAS,Renon–Prausnitz and Chen–Bagley models to correlate H^Eof studied mixtures is tested,and the agreement between experimental and theoretical results is satisfactory.Each model includes a self-association equilibrium constant that represents hydrogen bonding and an adjustable parameter that reflects physical interactions.展开更多
Four solid complexes of rare earth isothiocyanates with glycine were synthesized. They were characterized by chemical analysis, elemental analysis, Infrared spectra, X-ray powder diffraction and TO-DSC analysis. Their...Four solid complexes of rare earth isothiocyanates with glycine were synthesized. They were characterized by chemical analysis, elemental analysis, Infrared spectra, X-ray powder diffraction and TO-DSC analysis. Their chemical formulae were proved to be RE(NCS)2.Gly .H2O, where RE is La, Ce, Pr or Nd. The integral heats of solution of RE(NCS)3.3Gly. H2O in water, of RE(NCS)2. 7H2O in aqueous glycine solution and of glycine in water have been measured calorimetricaliy at 298. 15K. By means of a thermochemical cycle suggested in this paper, the standard molar enthalpies of formation for RE(NCS)2. 3Gly.H2O(c) were obtained and their lattice energies were calculated.展开更多
The integral heat of solution of REBr 3·3Gly·3H 2O(RE=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Y; Gly is glycine) in water, REBr 3· n H 2O(RE=La, Ce and Pr, n =7; RE=Nd, Sm, Eu, Gd, Tb, Dy and Y, n...The integral heat of solution of REBr 3·3Gly·3H 2O(RE=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Y; Gly is glycine) in water, REBr 3· n H 2O(RE=La, Ce and Pr, n =7; RE=Nd, Sm, Eu, Gd, Tb, Dy and Y, n =6) in aqueous glycine solution and glycine in water have been measured calorimetrically at 298 15±0 15 K. By means of a thermochemical cycle suggested in this paper, the standard molar enthalpies of formation of REBr 3·3Gly·3H 2O have been obtained and their lattice energies have been calculated.展开更多
The parameters of embedded atom method for elements Ce, Th and Yb were determined by fitting the lattice constants, the cohesive energy, the monovacancy formation energy and the bulk modulus of elements. The alloy pot...The parameters of embedded atom method for elements Ce, Th and Yb were determined by fitting the lattice constants, the cohesive energy, the monovacancy formation energy and the bulk modulus of elements. The alloy potential was taken as the form of Johnson′s. The formation enthalpies of Th-Ce, Th-Yb and Ce-Yb binary alloys systems and Ce-Th-Yb ternary alloy were calculated with the present embedded atom potentials. The calculations for binary alloys are in good agreement with the results calculated with Miedema′s theory. As for the ternary alloy, the calculated formation enthalpies are in good agreement with those extrapolated from the formation enthalpies of constitutive binary alloys by Toop′s model.展开更多
The combustion energies of fourteen solid complexes of lanthanide nitrate with alanine were determined. The standard enthalpies of combustion, Δ c,coor(s) H °, and standard enthalpies of formation, Δ ...The combustion energies of fourteen solid complexes of lanthanide nitrate with alanine were determined. The standard enthalpies of combustion, Δ c,coor(s) H °, and standard enthalpies of formation, Δ f,coor(s) H °, were calculated for these complexes. The relationship of Δ c,coor(s) H ° and Δ f,coor(s) H ° with the atomic numbers of the elements in the lanthanide series were examined. The results show that a certain amount of covalence is present in the chemical bond between the lanthanide cations and alanine.展开更多
The enthalpies of mixing for the PbCl_2-NaCl-BaCl_2 ternary molten salt mixtures have been measured along four iso-αPbCl_2 Iines by using a SETARAM calorimeter at 873 K.The results show that the molar enthalpy of mix...The enthalpies of mixing for the PbCl_2-NaCl-BaCl_2 ternary molten salt mixtures have been measured along four iso-αPbCl_2 Iines by using a SETARAM calorimeter at 873 K.The results show that the molar enthalpy of mixing between iso-αPbCl_2 liquid binary subsystems PbCl_2-NaCl and PbCl_2-BaCl_2 is near zero.approximately fitting the partial ideal solution model.展开更多
The modified embedded atom method proposed by authors has been applied to calculating the enthalpies of formation of random alloys and the ordered intermetallic compounds for noble metal binary systems bearing Rh or I...The modified embedded atom method proposed by authors has been applied to calculating the enthalpies of formation of random alloys and the ordered intermetallic compounds for noble metal binary systems bearing Rh or Ir. The present results are in good agreement with those of Miedema theory, available experiments and the first-principles quantum mechanics calculations. The present results indicate that Cu-Rh, Cu-lr, Ag-Rh, Ag-lr, Au-Rh, Au-lr, Pd-Rh and Pd-lr systems are repulsive, however, IMi-Rh, Ni-lr, Pt-lr, Pt-Rh and Rh-lr systems form solid solutions and Ni-Rh, Ni-lr and Pt-Rh show ordering tendency.展开更多
The artificial neural network (ANN) and the pattern recognition were applied to study the correlation of enthalpies of fusion for divalent rare earth halides with their microstructural parameters,such as ionic radius ...The artificial neural network (ANN) and the pattern recognition were applied to study the correlation of enthalpies of fusion for divalent rare earth halides with their microstructural parameters,such as ionic radius and electronegativity. The model,represented by a back-propagation netal network, was trained with a 12 set of published data for divalent rare earth halides and then was used to predict the unknown ones. Also the criterion equations were ptesented to determine the enthalpies of fuSion for divalent rare earth halides using pattern recognition in mis work. The results from the model in ANN and criterion equations are in very good agreement with reference data.展开更多
The treatment of RECl3.xH2O (RE = Ho, Er, Tm, Yb, Lu; x = 3-4) with sodium diethyldithiocarbamate (NaEtEdtc-3H2O) and 1,10-phenanthroline hydrate (o-phen.H2O) in absolute ethanol yielded five ternary solid compl...The treatment of RECl3.xH2O (RE = Ho, Er, Tm, Yb, Lu; x = 3-4) with sodium diethyldithiocarbamate (NaEtEdtc-3H2O) and 1,10-phenanthroline hydrate (o-phen.H2O) in absolute ethanol yielded five ternary solid complexes RE(EtEdtC)a(phen). IR spectra of the complexes showed that RE^3+ coordinated to two sulfur atoms in NaEt2dtc and two nitrogen atoms in o-phen. The constant-volume energies of combustion of the complexes have been determined by a precise rotating-bomb calorimeter at 298.15 K. The standard enthalpies of combustion and standard enthalpies of formation were calculated.展开更多
An experimental characterization of the Van der Waals forces involved in volatile organic compounds (VOC) dissolved into stationary phases of gas liquid chromatography (GLC) has been started at the beginning of the se...An experimental characterization of the Van der Waals forces involved in volatile organic compounds (VOC) dissolved into stationary phases of gas liquid chromatography (GLC) has been started at the beginning of the seventies. This field has been reactivated from 1994 thanks to a fruitful cooperation between our CNRS team and the group of Ervin Kováts at the Federal Polytechnic School of Lausanne. The applied strategy can be summarized, in the first instance, as the experimental measurement of accurate and superabundant mutual affinities of a limited number of VOC and stationary phases and their processing using an original tool named Multiplicative Matrix Analysis (MMA). Then, in the second stage, the obtained results have been compared with molecular properties well established, as the Van der Waals molecular volume, the refraction index and the polar surface area (PSA), in order to get generalized values for any compound. The present study summarizes the positive results developed in our three last papers on this topic (2013, 2016 and 2018), as well as the attempt to overcome the negative ones using enthalpies of vaporization.展开更多
Solid complexes, RE(Et2dtc)3(phen) (RE=La, Pr, Nd, Sm-Lu), were synthesized hydrated lanthanide chlorides in absolute ethanol. The constant-volume combustion energies of complexes, △cU, were determined by a precise r...Solid complexes, RE(Et2dtc)3(phen) (RE=La, Pr, Nd, Sm-Lu), were synthesized hydrated lanthanide chlorides in absolute ethanol. The constant-volume combustion energies of complexes, △cU, were determined by a precise rotating-bomb calorimeter at 298.15 K. The standard enthalpies of combustion, AcHmθ, and standard enthalpies of formation, AfHmθ, were calculated for these complexes, respectively. The experiment results showed the "tripartite effect"of rare earth.展开更多
An electrostatic bond energy model is formulated to fit the enthalpies of formation and dipole moments of the alkanes and chloroalkanes. In this model, the charge distributions are calculated by an electrostatic appro...An electrostatic bond energy model is formulated to fit the enthalpies of formation and dipole moments of the alkanes and chloroalkanes. In this model, the charge distributions are calculated by an electrostatic approach similar to the "MSE" method, and the enthalpy of formation of a molecule is the sum of the bond energy terms plus the electrostatic energy of the interactions between the charges on all atoms. All parameters of this model are obtained by parameterization. The calculated dipole moments for 13 chloroalkanes and enthalpies of formation for 19 alkanes and non-geminal chloroalkanes agree with the determined values very well. To calculate the enthalpies of formation of geminal chloroalkanes, a correction mainly attributed to the van der Waals interactions in the geminal substituted group, about 24 kJ/mol per pair of geminal chlorine atoms, is introduced.展开更多
文摘The atomic structural parameter P-i = (Z(i)*/n(i)*) (1 + n(i)*/n(i)) (1 + m(i)/Z) and the molecular structural parameter [GRAPHICS] are defined. The standard formation enthalpies (Delta(f)H(m)(phi)) of 74 species of rare earth compounds were studied with P, and the correlation coefficient is R > 0.94. The structural factors and the properties of rare earth compounds are influenced by the Z(i)*, n(i)*, n(i), m(i), Z. This study has special referential value to predict the properties of rare earth compounds.
基金Funded by the Nature Science Foundation of China (No. 29773033)
文摘The topological index F* is defined and obtained by the method of a non-dimensional unit calculation in which three matrices multiply with each other. These matrices represent the connective cases of atoms in a molecule, the structural features of atoms on top and the bonded cases of the adjacent atoms respectively. The standard formation enthalpies of ABn(g) molecules were correlated with F’* (A = C, Al, Si, Ti, Zr, B = F, Cl, Br, I, H, n=1 -4) and these correlation coefficients are all more than 0.96. Some molecules (e.g CH4, SiH4,etc. )can be preferably handled by F* but can not be dealt with by other topological indices. By contrast to traditional hydrogen suppressed graph, the contribution of hydrogen atoms to structures and properties of molecules is considered.
基金financially supported by the National Natural Science Foundation of China (Nos. 51274083 and 51074062)
文摘Balance solubility products and enthalpy of for- mation for NbC0.75, NbC0.85, NbC0.88, NbC and NbN in oriented silicon steels were calculated and compared quali- tatively. Meanwhile, the mixing enthalpies of these five Nb compounds were calculated based on Miedema Model. The results show that the solubility products of Nb compounds in ferrite and austenite meet the following relationship, NbC0.75 〉 NbC0.85 〉 NbC0.88 〉 NbC 〉 NbN and NbN has the minimum enthalpy of formation. It indicates that NbN easily precipitate out, but it is more difficult for NbC0.75.
基金the National Natural Science Foundation ofChina (No.50764006)Young Foundation of Kunming University of Science and Tech-nology (No.KKZ200727021)the Applied Fundamental Research Foundation ofYunnan Province (Nos.2007E039M and 2006E0021M).
文摘The mixing enthalpies of 23 binary liquid alloys are calculated by molecular interaction volume model (MIVM), which is a two-parameter model with the partial molar infinite dilute mixing enthalpies. The predicted values are in agreement with the experimental data and then indicate that the model is reliable and convenient.
文摘The enthalpies of solution in water of complexes of RE(NO 3) 3 (RE=La~Nd, Sm~Lu, Y) with L α Histidine (His) were measured at 298.15 K. The standard enthalpies of formation of RE(His) 3+ (aq) were calculated. The 'tetrad effect' regularity was observed from the curve, which is the enthalpies of solution plotted against the atomic numbers of the elements in lanthanide series.
文摘'White powdery tungstic acid' has been used for preparing various types of tungsten-containing compounds due to its high reactivity. The present paper covers the standard molar enthalpies of formation, △H0/f of three tungsten- containing acids. The values found for 'white powdery tungstic acid' WO3·1. 68H2O, 'yellow tungstic acid' WO3·1. 20H2O and dodecatungstophosphoric acid H3(PW12O40)·25H2O at 298. 15 K were-(1312±1), - (1192±1) and -(18150±13) kJ mol-1, respectively.
文摘Excess molar enthalpies,H^E,for the binary mixtures of 2-pentanol with n-alkanes(n-heptane,n-octane,and nnonane)have been determined at three different temperatures T=(293.15,298.15 and 303.15)K and normal atmospheric pressure over the entire composition range using a Calvet microcalorimeter.All mixtures show endothermic mixing with the maximum values of the excess enthalpies occurring in the n-alkane-rich region.The H^Edata are smoothed using Redlich–Kister equation.The applicability of the Treszczanowicz–Benson,ERAS,Renon–Prausnitz and Chen–Bagley models to correlate H^Eof studied mixtures is tested,and the agreement between experimental and theoretical results is satisfactory.Each model includes a self-association equilibrium constant that represents hydrogen bonding and an adjustable parameter that reflects physical interactions.
基金Projects supported by the National Natural Science Foundation of China.
文摘Four solid complexes of rare earth isothiocyanates with glycine were synthesized. They were characterized by chemical analysis, elemental analysis, Infrared spectra, X-ray powder diffraction and TO-DSC analysis. Their chemical formulae were proved to be RE(NCS)2.Gly .H2O, where RE is La, Ce, Pr or Nd. The integral heats of solution of RE(NCS)3.3Gly. H2O in water, of RE(NCS)2. 7H2O in aqueous glycine solution and of glycine in water have been measured calorimetricaliy at 298. 15K. By means of a thermochemical cycle suggested in this paper, the standard molar enthalpies of formation for RE(NCS)2. 3Gly.H2O(c) were obtained and their lattice energies were calculated.
文摘The integral heat of solution of REBr 3·3Gly·3H 2O(RE=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Y; Gly is glycine) in water, REBr 3· n H 2O(RE=La, Ce and Pr, n =7; RE=Nd, Sm, Eu, Gd, Tb, Dy and Y, n =6) in aqueous glycine solution and glycine in water have been measured calorimetrically at 298 15±0 15 K. By means of a thermochemical cycle suggested in this paper, the standard molar enthalpies of formation of REBr 3·3Gly·3H 2O have been obtained and their lattice energies have been calculated.
文摘The parameters of embedded atom method for elements Ce, Th and Yb were determined by fitting the lattice constants, the cohesive energy, the monovacancy formation energy and the bulk modulus of elements. The alloy potential was taken as the form of Johnson′s. The formation enthalpies of Th-Ce, Th-Yb and Ce-Yb binary alloys systems and Ce-Th-Yb ternary alloy were calculated with the present embedded atom potentials. The calculations for binary alloys are in good agreement with the results calculated with Miedema′s theory. As for the ternary alloy, the calculated formation enthalpies are in good agreement with those extrapolated from the formation enthalpies of constitutive binary alloys by Toop′s model.
文摘The combustion energies of fourteen solid complexes of lanthanide nitrate with alanine were determined. The standard enthalpies of combustion, Δ c,coor(s) H °, and standard enthalpies of formation, Δ f,coor(s) H °, were calculated for these complexes. The relationship of Δ c,coor(s) H ° and Δ f,coor(s) H ° with the atomic numbers of the elements in the lanthanide series were examined. The results show that a certain amount of covalence is present in the chemical bond between the lanthanide cations and alanine.
文摘The enthalpies of mixing for the PbCl_2-NaCl-BaCl_2 ternary molten salt mixtures have been measured along four iso-αPbCl_2 Iines by using a SETARAM calorimeter at 873 K.The results show that the molar enthalpy of mixing between iso-αPbCl_2 liquid binary subsystems PbCl_2-NaCl and PbCl_2-BaCl_2 is near zero.approximately fitting the partial ideal solution model.
基金This work is partly supported by The National Natural Science Foundation of China(59762001)Guangxi Natural Science Foundation(9811031)the Foundation of Ten-Hundred-Thousand Project of Personnel Department of Guangxi(2000209).
文摘The modified embedded atom method proposed by authors has been applied to calculating the enthalpies of formation of random alloys and the ordered intermetallic compounds for noble metal binary systems bearing Rh or Ir. The present results are in good agreement with those of Miedema theory, available experiments and the first-principles quantum mechanics calculations. The present results indicate that Cu-Rh, Cu-lr, Ag-Rh, Ag-lr, Au-Rh, Au-lr, Pd-Rh and Pd-lr systems are repulsive, however, IMi-Rh, Ni-lr, Pt-lr, Pt-Rh and Rh-lr systems form solid solutions and Ni-Rh, Ni-lr and Pt-Rh show ordering tendency.
文摘The artificial neural network (ANN) and the pattern recognition were applied to study the correlation of enthalpies of fusion for divalent rare earth halides with their microstructural parameters,such as ionic radius and electronegativity. The model,represented by a back-propagation netal network, was trained with a 12 set of published data for divalent rare earth halides and then was used to predict the unknown ones. Also the criterion equations were ptesented to determine the enthalpies of fuSion for divalent rare earth halides using pattern recognition in mis work. The results from the model in ANN and criterion equations are in very good agreement with reference data.
基金[This work was financially supported by the Natural Science Foundation of China (No. 20171036), the Natural Science Foundation of Shaanxi Province (Nos. 01JK229, FF02328 and 05JK291) and Postgraduate Foundation of China.]
文摘The treatment of RECl3.xH2O (RE = Ho, Er, Tm, Yb, Lu; x = 3-4) with sodium diethyldithiocarbamate (NaEtEdtc-3H2O) and 1,10-phenanthroline hydrate (o-phen.H2O) in absolute ethanol yielded five ternary solid complexes RE(EtEdtC)a(phen). IR spectra of the complexes showed that RE^3+ coordinated to two sulfur atoms in NaEt2dtc and two nitrogen atoms in o-phen. The constant-volume energies of combustion of the complexes have been determined by a precise rotating-bomb calorimeter at 298.15 K. The standard enthalpies of combustion and standard enthalpies of formation were calculated.
文摘An experimental characterization of the Van der Waals forces involved in volatile organic compounds (VOC) dissolved into stationary phases of gas liquid chromatography (GLC) has been started at the beginning of the seventies. This field has been reactivated from 1994 thanks to a fruitful cooperation between our CNRS team and the group of Ervin Kováts at the Federal Polytechnic School of Lausanne. The applied strategy can be summarized, in the first instance, as the experimental measurement of accurate and superabundant mutual affinities of a limited number of VOC and stationary phases and their processing using an original tool named Multiplicative Matrix Analysis (MMA). Then, in the second stage, the obtained results have been compared with molecular properties well established, as the Van der Waals molecular volume, the refraction index and the polar surface area (PSA), in order to get generalized values for any compound. The present study summarizes the positive results developed in our three last papers on this topic (2013, 2016 and 2018), as well as the attempt to overcome the negative ones using enthalpies of vaporization.
基金supported by the National Natural Science Foundation of China(Grant No.20171036)Education Committee of Shaanxi Province(No.01JK229)Northwest University(02NW02)
文摘Solid complexes, RE(Et2dtc)3(phen) (RE=La, Pr, Nd, Sm-Lu), were synthesized hydrated lanthanide chlorides in absolute ethanol. The constant-volume combustion energies of complexes, △cU, were determined by a precise rotating-bomb calorimeter at 298.15 K. The standard enthalpies of combustion, AcHmθ, and standard enthalpies of formation, AfHmθ, were calculated for these complexes, respectively. The experiment results showed the "tripartite effect"of rare earth.
文摘An electrostatic bond energy model is formulated to fit the enthalpies of formation and dipole moments of the alkanes and chloroalkanes. In this model, the charge distributions are calculated by an electrostatic approach similar to the "MSE" method, and the enthalpy of formation of a molecule is the sum of the bond energy terms plus the electrostatic energy of the interactions between the charges on all atoms. All parameters of this model are obtained by parameterization. The calculated dipole moments for 13 chloroalkanes and enthalpies of formation for 19 alkanes and non-geminal chloroalkanes agree with the determined values very well. To calculate the enthalpies of formation of geminal chloroalkanes, a correction mainly attributed to the van der Waals interactions in the geminal substituted group, about 24 kJ/mol per pair of geminal chlorine atoms, is introduced.