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1.
Gerhard Kahl Elisabeth Sch?ll-Paschinger Andreas Lang 《Monatshefte für Chemie / Chemical Monthly》2001,308(5):1413-1432
Compared to the simple one-component case, the phase behaviour of binary liquid mixtures shows an incredibly rich variety of phenomena. In this contribution we restrict ourselves to so-called binary symmetric mixtures, i.e. where like-particle interactions are equal (Φ11(r) = Φ22(r)), whereas the interactions between unlike fluid particles differ from those of likes ones (Φ11(r) ≠ Φ12(r)). Using both the simple mean spherical approximation and the more sophisticated self-consistent Ornstein-Zernike approximation, we have calculated the structural and thermodynamic properties of such a system and determine phase diagrams, paying particular attention to the critical behaviour (critical and tricritical points, critical end points). We then study the thermodynamic properties of the same binary mixture when it is in thermal equilibrium with a disordered porous matrix which we have realized by a frozen configuration of equally sized particles. We observe – in qualitative agreement with experiment – that already a minute matrix density is able to lead to drastic changes in the phase behaviour of the fluid. We systematically investigate the influence of the external system parameters (due to the matrix properties and the fluid–matrix interactions) and of the internal system parameters (due to the fluid properties) on the phase diagram. 相似文献
2.
Jarmila Mlynariková Marta Chrenková Vladimír Danielik Vladimír Daněk Oldřich Matal 《Monatshefte für Chemie / Chemical Monthly》2008,139(2):77-80
Summary. The phase diagram of the binary system NaF–NaBF4 was determined using the thermal analysis method. Subsequent coupled analysis of the thermodynamic and phase diagram data
was carried out to calculate the thermodynamically consistent phase diagram. The system NaF–NaBF4 forms a simple eutectic phase diagram with the calculated coordinates of the eutectic point: 8.1 mol% NaF, 91.9 mol% NaBF4, and 385.7°C. The probable inaccuracy in the calculated binary phase diagram is 9°C. 相似文献
3.
Summary. Solubility measurements as a function of temperature have been shown to be a powerful tool for the determination of thermodynamic
properties of sparingly-soluble transition metal carbonates. In contrast to calorimetric methods, such as solution calorimetry
or drop calorimetry, the evaluation of solubility data avoids many systematic errors, yielding the enthalpy of solution at
298.15 K with an estimated uncertainty of ±3 kJ · mol−1. A comprehensive set of thermodynamic data for otavite (CdCO3), smithsonite (ZnCO3), hydrozincite (Zn5(OH)6(CO3)2), malachite (Cu2(OH)2CO3), azurite (Cu3(OH)2(CO3)2), and siderite (FeCO3) was derived. Literature values for the standard enthalpy of formation of malachite and azurite were disproved by these solubility
experiments, and revised values are recommended. In the case of siderite, data for the standard enthalpy of formation given
by various data bases deviate from each other by more than 10 kJ · mol−1 which can be attributed to a discrepancy in the auxiliary data for the Fe2+ ion. A critical evaluation of solubility data from various literature sources results in an optimized value for the standard
enthalpy of formation for siderite. The Davies approximation, the specific ion-interaction theory, and the Pitzer concept are used for the extrapolation of the solubility constants to zero ionic strength in order to obtain standard thermodynamic
properties valid at infinite dilution, T = 298.15 K, and p = 105 Pa. The application of these electrolyte models to both homogeneous and heterogeneous (solid-solute) equilibria in aqueous
solution is reviewed.
Received June 26, 2001. Accepted July 2, 2001 相似文献
4.
Three mole fractions of the binary system K-palmitate/glycerol (KC16/Gl) xKC16 = 0.30, 0.37 and 0.50 have been investigated as a function of temperature by small- and wide-angle X-ray diffraction investigations
and differential scanning calorimetry (DSC) measurements. The existence of a gel-like region, named G1 in the preliminary binary phase diagram [4], could not be confirmed. Consequently, a corrected version of the phase diagram
of the KC16/Gl system is established. According to this corrected phase diagram at low K-palmitate concentrations, xKC16 < 0.25, the transitions crystalline phase (C) ⇆ hexagonal phase, chains fluid (Hα) ⇆ isotropic, micellar phase (S) occur with rising temperature. At xKC16 > 0.25 the transitions C ⇆ gel phase (G) ⇆ lamellar phase, chains fluid (Lα) were observed. X-ray diffraction and DSC measurements provided concordant results. Only differences in the phase transition
temperatures from DSC curves obtained at rising and falling temperatures were observed. The phase transitions C ⇆ G, G ⇆ Lα and G ⇆ Hα correlate with a sharp shift in the d value of the first small-angle reflection. The occurrence of the G phase is accompanied by a distinct split of the first
small-angle reflections. Simultaneously, the wide-angle reflections change and the peak intensity is reduced.
Received: 14 April 1999 Accepted: 28 June 1999 相似文献
6.
The spectroscopic properties of M–SiO and M–(SiO)2 (1–1 and 1–2 complexes with M = Cu, Ag, or Au) have been theoretically studied. It has been shown that both M–SiO and M–(SiO)2 compounds in their ground state are bent with a metal–Si bonded structure. The calculated M(ns) spin density agrees well with the electron spin resonance experimental data. From a topological analysis, it has been shown
that a rather large charge transfer occurs from the metal towards the SiO moiety, and that the M–Si bond energy correlates with the electron density located at the M–Si bond path (bond critical point).
Received: 6 July 2000 / Accepted: 11 October 2000 / Published online: 19 January 2001 相似文献
7.
Summary. Binary thermodynamic data, successfully used for phase diagram calculations of binary systems Ag–In, Ag–Sb, and In–Sb, were
used for prediction of phase equilibria in ternary Ag–In–Sb system at 200°C. Symmetrical Redlich–Kister–Muggianu model for ternary thermodynamic function calculation was proved to be best valid in this ternary system. Predicted equilibria
were compared with experimentally (SEM, EDX) determined composition of phases in chosen alloys after long term annealing and
with the results of DTA measurements. 相似文献
8.
The most stable structures of V
x
O
y
+/V
x
O
y
(x=1, 2, y=1–5) clusters and their interaction with O2 are determined by density functional calculations, the B3LYP functional with the 6-31G* basis set. The nature of the bonding
of these clusters and the interaction with O2 have been studied by topological analysis in the framework of both the atoms-in-molecules theory of Bader and the Becke–Edgecombe
electron localization function. Bond critical points are localized by means of the analysis of the electron density gradient
field, ∇ρ(r), and the electron localization function gradient field, ∇η(r). The values of the electron density properties, i.e., electron density, ρ(r), Laplacian of the electron density, ∇2ρ(r), and electron localization function, η(r), allow the nature of the bonds to be characterized, and linear correlation is found for the results obtained in both gradient
fields. Vanadium-oxygen interactions are characterized as unshared-electron interactions, and linear correlation is observed
between the electron density properties and the V–O bond length. In contrast, O2 units involve typical shared-electron interactions, as for the dioxygen molecule. Four different vanadium–oxygen interactions
are found and characterized: a molecular O2 interaction, a peroxo O2
2− interaction, a superoxo O2
− interaction and a side-on O2
− interaction.
Received: 15 October 2001 / Accepted: 30 January 2002 / Published online: 24 June 2002 相似文献
9.
Solubility measurements as a function of temperature have been shown to be a powerful tool for the determination of thermodynamic properties of sparingly-soluble transition metal carbonates. In contrast to calorimetric methods, such as solution calorimetry or drop calorimetry, the evaluation of solubility data avoids many systematic errors, yielding the enthalpy of solution at 298.15 K with an estimated uncertainty of ±3 kJ · mol−1. A comprehensive set of thermodynamic data for otavite (CdCO3), smithsonite (ZnCO3), hydrozincite (Zn5(OH)6(CO3)2), malachite (Cu2(OH)2CO3), azurite (Cu3(OH)2(CO3)2), and siderite (FeCO3) was derived. Literature values for the standard enthalpy of formation of malachite and azurite were disproved by these solubility experiments, and revised values are recommended. In the case of siderite, data for the standard enthalpy of formation given by various data bases deviate from each other by more than 10 kJ · mol−1 which can be attributed to a discrepancy in the auxiliary data for the Fe2+ ion. A critical evaluation of solubility data from various literature sources results in an optimized value for the standard enthalpy of formation for siderite. The Davies approximation, the specific ion-interaction theory, and the Pitzer concept are used for the extrapolation of the solubility constants to zero ionic strength in order to obtain standard thermodynamic properties valid at infinite dilution, T = 298.15 K, and p = 105 Pa. The application of these electrolyte models to both homogeneous and heterogeneous (solid-solute) equilibria in aqueous solution is reviewed. 相似文献
10.
S. Odinaev D. M. Akdodov N. Sh. Sharifov Kh. Mirzoaminov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(6):954-959
Analytical expressions obtained earlier are used to numerically calculate the dynamic coefficients of the bulk ην(ω) and shear η
s
(ω) viscosity and the corresponding modules of their bulk K(ω) and shear μ(ω) elasticity at a certain choice of the model of solution structure in an approximation of the osmotic solution
theory. The potential energy of the interaction between ions Φ
ab
(r) was taken as the sum of the Lennard-Jones potential and the generalized Debye potential, taking into account the configuration
and size of ions. In this approximation, the viscoelastic properties of the NaCl water solution were numerically calculated
over a wide interval of change in the thermodynamic parameters and frequency ranges. Satisfactory agreement with the literature
experimental data was obtained. 相似文献
11.
Marián Kucharík František Šimko Vladimír Danielik Miroslav Boča Roman Vasiljev 《Monatshefte für Chemie / Chemical Monthly》2007,138(12):1211-1215
Summary. The phase diagram of the system Na3AlF6–NaVO3 was determined by means of thermal analysis. The system is a simple binary eutectic one. The eutectic point was estimated
at x(NaVO3) = 0.975 and t
eut = 617°C. The XRD patterns of samples after thermal analysis revealed the presence of cryolite and NaVO3 only supporting the above assumption of a simple eutectic binary system. 相似文献
12.
We start from a classical statistical–mechanical theory for the internal energy in terms of three- and four-body correlation
functions g
3 and g
4 for homogeneous atomic liquids like argon, with assumed central pair interactions f(rij){\phi(r_{ij})} . The importance of constructing the partition function (pf) as spatial integrals over g
3, g
4 and f{\phi} is stressed, together with some basic thermodynamic consequences of such a pf. A second classical example taken for two-body
interactions is the so-called one-component plasma in two dimensions, for a particular coupling strength treated by Alastuey
and Jancovici (J Phys (France) 42:1, 1981) and by Fantoni and Tellez (J Stat Phys 133:449, 2008). Again thermodynamic consequences
provide a particular focus. Then quantum–mechanical assemblies are treated, again with separable many-body interactions. The
example chosen is that of an N-body inhomogeneous extended system generated by a one-body potential energy V(r). The focus here is on the diagonal element of the canonical density matrix: the so-called Slater sum S(r, β), related to the pf by pf(b) = òS(r, b)d[(r)\vec]{{\rm pf}(\beta) = \int {S({\bf r}, \beta)}d\vec {r}}, β = (k
B
T)−1. The Slater sum S(r, β) can be related exactly, via a partial differential equation, to the one-body potential V(r), for specific choices of V which are cited. The work of Green (J Chem Phys 18:1123, 1950), is referred to for a generalization, but now perturbative,
to two-body forces. Finally, to avoid perturbation series, the work concludes with some proposals to allow the treatment of
extended assemblies in which regions of long-range ordered magnetism exist in the phase diagram. One of us (Z.D.Z.) has recently
proposed a putative pf for a three-dimensional (3D) Ising model, based on two, as yet unproved, conjectures and has pointed
out some important thermodynamic consequences of this pf. It would obviously be of considerable interest if such a pf, together
with conjectures, could be rigorously proved. 相似文献
13.
By using the CALPHAD technique, an optimization of the binary EuCl3–MCl (M = Na, K, Rb, Cs) systems has been carried out. To describe the Gibbs energies of liquid phases in these systems the
new modified quasi-chemical model was used in the pair-approximation for short-range ordering. From the measured phase equilibrium
data and the experimental thermo-chemical properties, the EuCl3–MCl phase diagrams were optimized and calculated. A set of thermodynamic functions has been optimized based on an interactive
computer-assisted analysis. The calculated phase diagrams and thermodynamic data are self-consistent. 相似文献
14.
Jean-Fran?ois Létard Guillaume Chastanet Olivier Nguyen Silvia Marcén Mathieu Marchivie Philippe Guionneau Daniel Chasseau Philipp Gütlich 《Monatshefte für Chemie / Chemical Monthly》2003,134(2):165-182
Summary. In the present review, we reexamine the photomagnetic properties of the [Fe(PM-BiA)2(NCS)2], cis-bis(thiocyanato)-bis[(N-2′-pyridylmethylene)-4-(aminobiphenyl)]iron(II), compound which exhibits, depending on the synthetic method, an exceptionally
abrupt spin transition (phase I) with a very narrow hysteresis (T
1/2↓ = 168 K and T
1/2↑ = 173 K) or a gradual spin conversion (phase II) occurring at 190 K. In both cases, light irradiation in the tail of the 1MLCT-LS absorption band, at 830 nm, results in the population of the high-spin state according to the light-induced excited
spin-state trapping (LIESST) effect. The capacity of a compound to retain the light-induced HS information, estimated through
the T(LIESST) experiment, is determined for both phases. Interestingly, the shape of the T(LIESST) curve is more gradual for the phase II than for the phase I and the T(LIESST) value is found considerably lower in the case of the phase II. The kinetics parameters involved in the photoinduced high-spin→low-spin relaxation process are estimated for both phases.
From these data, the experimental T(LIESST) curves are simulated and the particular influence of the cooperativity as well as of the parameters involved in the
thermally activated and tunneling regions are discussed. The Light-Induced Thermal Hysteresis (LITH), originally described
for the strongly cooperative phase I, is also reinvestigated. The quasi-static LITH loop is determined by recording the photostationary points in the warming
and cooling branches.
Corresponding authors. E-mail: letard@icmcb.u-bordeaux.fr
Received August 26, 2002; accepted August 30, 2002 相似文献
15.
S. V. Blokhina N. V. Usol’tseva M. V. Ol’khovich A. V. Sharapova 《Russian Chemical Bulletin》2008,57(12):2548-2553
The thermodynamic functions of dissolution of n-alkanes (C7–C9) and n-alkanols (C5–C8) in the liquid-crystalline and isotropic phases of polypropyleneimine dendrimer of the first generation at infinite dilution
were determined by the reversed-phase gas chromatography. The dependences of the thermodynamic parameters of sorbates on the
phase state of the dendrite solvent, hydrocarbon chain length, and polarity of low-molecular-weight components of mesogenic—nonmesogenic
binary systems were considered. The role of dispersion forces and specific intermolecular interactions in the solutions under
study was estimated. Saturated hydrocarbons are more compatible with columnar phases of the dendrimer than alcohols. 相似文献
16.
Francisco Ros Pilar Jiménez María Victoria Roux 《Monatshefte für Chemie / Chemical Monthly》2007,138(10):941-949
Summary. The cohesion potential energy of the crystal of one enantiomer of ethyl 3-cyano-3-(3,4-dimethyloxyphenyl)-2,2,4-trimethylpentanoate,
−47.7 ± 0.1 kJ mol−1 (0–90°C), was found out from the heat of sublimation (123.2 ± 5.1 kJ mol−1, 78.6°C) and the kinetic energies for the gas phase and the crystal. It was found that the entropy function of Debye’s theory of solids mathematically agreed with the vibrational entropy of the gas (variationally obtained), allowing to disclose
the vibrational energy using the Debye energy function (E
vib 835.0 kJ mol−1 (78.6°C), E
0 included). E
kin for the crystal (771.1 kJ mol−1 (78.6°C)) was obtained by Debye’s theory with the experimental heat capacity. The cohesion energy represented a moderate part of the sublimation energy.
The cohesion energy of the racemic crystal, −44.2 kJ mol−1, was obtained by the heat of formation of the crystal in the solid state (3.0 kJ mol−1, 83.3°C) and E
kin for the crystal (by Debye’s theory). The decrease in cohesion on formation of the crystal accounted for the energy of formation. The change in potential
energy on liquefaction of the racemate from the gas state was disclosed obtaining added-up E
vib + rot for the liquid in the way as to E
vib for the gas, the Debye entropy function being increasedly suited for the liquid (E
vib + rot 763.4 kJ mol−1 (115.4°C)). Positive ΔE
pot, 13.0 kJ mol−1, arised from the increase in electronic energy (Δ
l
νmean − 154.3 cm−1, by the dielectric nature of the liquid), added to the cohesion energy. 相似文献
17.
Carina M. M. Machado Paula Gameiro Helena M. V. M. Soares 《Journal of solution chemistry》2008,37(5):603-617
The complexation behavior of eight M–(buffer)
x
–(OH)
y
systems involving two divalent ions (cobalt and nickel) and four zwitterionic biological buffers (AMPSO, DIPSO, TAPS and
TAPSO) were characterized. Complex formation was detected for all eight M–(buffer)
x
–(OH)
y
systems studied, but fully defined final models were obtained for only four of these systems. For systems involving cobalt
or nickel with AMPSO or TAPS, a complete characterization of the systems was not possible in the studied buffer pH-range.
Metal complexation was studied by glass-electrode potentiometry (GEP) and UV-Vis spectroscopy at 25.0 °C and I=0.1 mol⋅dm−3 KNO3 ionic strength. For the Ni–(L)
x
–(OH)
y
and Co–(L)
x
–(OH)
y
systems, with L = TAPSO or DIPSO, the proposed final models and overall stability constants were obtained by combining results
from both techniques. For the Ni–(L)
x
–(OH)
y
systems, the measured values of the stability constants are log 10
β
NiL=3.0±0.1 and log 10
β
NiL2=4.8±0.1 for L = TAPSO, and log 10
β
NiL=2.7±0.1 and log 10
β
NiL2=4.6±0.1 for L = DIPSO. For the Co–(L)
x
–(OH)
y
systems, the overall stability constants are log 10
β
CoL=2.2±0.1, log 10
β
CoL2=3.6±0.2 and log 10
β
CoL(OH)=7.6±0.1 for L = TAPSO, and log 10
β
CoL=2.0±0.1 and log 10
β
CoL(OH)=7.8±0.1 for L = DIPSO. For both buffers, the CoL(OH) species is characterized by a major structural rearrangement. 相似文献
18.
Raman scattering spectra and molecular conformations of bis(quaternaryammonium bromide)-water systems 总被引:1,自引:0,他引:1
The dimeric bis(quaternaryammonium bromide) surfactants, [Br−(CH3)2N+(C
m
H2
m
+1)—(CH2)
s
—(C
m
H2
m
+1)N+(CH3)2Br−, s = 2, 3 and m = 4, 6, 10 and 12, s = 6 and m = 8, 10, 12], have been synthesized and the phase maps of the sm6-8-water, sm6-10-water and sm6-12-water binary systems have
been determined (sm6-8 implies s = 6, m = 8). In order to examine the molecular structures of these solid samples and of their dimeric surfactant-water binary systems,
Raman spectra of the simple dimeric surfactants, sm2-4 and sm3-4, in which crystal structures of the trans- and cis-type conformations
have been determined by single-crystal X-ray diffraction analysis, have been investigated, and Raman bands characteristic
of these skeletal structures were found in the skeletal deformation region. On the basis of these characteristic Raman bands
for the two conformations, it has been concluded that the dimeric surfactants, sm6-8, sm6-10 and sm6-12 also take up a cis-type
conformation in the crystalline state. Furthermore, it has been found that the Raman bands in the C—H stretching, skeletal
stretching and CH2 scissoring regions are sensitive to phase structure.
Received: 21 July 1998 Accepted in revised form: 9 November 1998 相似文献
19.
Krisztina A. Vincze-Minya Alois Schausberger 《Monatshefte für Chemie / Chemical Monthly》2006,137(7):911-918
Summary. Melts of polyethylene-propylene-rubber (EPR, blends of linear polyethylene, linear polypropylene, and PE-PP copolymer) show phase separation. The influence of the phase morphology on the viscoelastic behaviour is studied with the
aid of the dynamical moduli. The measured moduli of the fraction of the linear homopolymer of an EPR agree with the moduli
calculated from the molar mass distribution of this fraction. In contrast, the copolymer fraction shows a strong rubber-like
behaviour (represented by a characteristic relaxation time spectrum). Mixtures of 80 wt% linear PP and of EPRs with low copolymer content are not rubber-like liquids. In addition, the moduli from them can be calculated from
the moduli of the components with the aid of Palierne’s emulsion model. This clearly reveals that the linear PP forms the matrix in this case. Mixtures of 80 wt% linear PP and of EPRs with high copolymer content show rubber-like behaviour and Palierne’s emulsion model is not applicable on them. Obviously, the copolymer fraction forms a physical network. 相似文献
20.
S. F. Ledenkov V. N. Vandyshev A. S. Molchanov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2012,86(6):959-964
Enthalpies of the interaction of protonated dopamine with a hydroxide ion in water-ethanol mixtures in the concentration range
of 0–0.8 EtOH mole fractions are measured calorimetrically. The neutralization process of dopamine hydrochloride is shown
to occur endothermally in solvents with an ethanol concentration of ≥0.5 mole fractions. Standard thermodynamic characteristics
(Δr
H
○, Δr
G
○, and Δr
S
○) of the first-step acid dissociation of dopamine hydrochloride in solutions are calculated with regard to the autoprotolysis
enthalpy of binary solvents. It is found that dissociation enthalpies vary within 9.1–64.8 kJ/mol, depending on the water-ethanol
solvent composition. 相似文献