Thermodynamic Excess Functions for Quasiternary Solid Solutions of Type M(X,Y,Z) I. The System Pb (S,Te,Se)

The excess free enthalpy of quasiternary systems of type M (X, Y, Z) with two sublattices, a mixed one (X, Y,Z) and a pure one (M), will be described in two ways: (1) by the interaction parameters of the three subregularly treated quasibinary subsystems and by one ternary parameter, and (2) by the cluster energies of 10 pyramidal clusters. It is shown that, for the spinodal miscibility gap in the special system Pb (S, Te, Se), both versions yield satisfying accordance of experiments and calculated results

X-Ray Diffraction Study of Methanol-Water Mixtures

X-ray diffraction patterns o f m ethanol-water mixtures with mole fractions of methanol molecules o f 0.1, 0.25 and 0.9 have been measured. The experimental structure functions of mixtures are compared with those of pure solvents and with recent Molecular Dynamics results. Difference structure functions similar to thermodynamic excess functions are introduced for the analysis of methanol-water interactions. The comparison of the total and the difference structure functions from experiments and simulations shows an overall good agreement.

A comprehensive thermodynamic investigation of water–ethanolamine mixtures at 10, 25, and 40 °C

The density, isobaric specific heat capacity, and isentropic compressibility of water–ethanolamine (W–EA) mixtures have been measured at three temperatures (10, 25, and 40 °C) over the entire composition range. The results were used to calculate various thermodynamic excess functions of these mixtures, namely: the excess molar volume [Formula: see text] excess molar isentropic and isothermal compressibilities [Formula: see text] excess molar isobaric and isochoric heat capacities [Formula: see text] and excess molar isobaric expansion [Formula: see text] The corresponding partial molar quantities for ethanolamine in the mixtures were also computed. These excess and partial molar quantities were compared with those observed earlier in the water – ethylene glycol (W–EG) (1) and in the water–2-methoxyethanol (W–ME) (2) mixtures. The similarities and differences in the properties of these systems are interpreted on the basis of the specific molecular features of the cosolvents and the concepts of cooperative fluctuations and hydrogen-bonding connectivity in liquid water and dilute aqueous solutions.

Thermodynamische Interpretation der Schmelzdiagramme binärer Systeme aus Methylchlorsilanen und Pyridazin bzw. Pyrazin

By analyzing the cooling curves and the resulting melting point diagrams of the chloromethylsilane- pyridazine and pyrazine systems the existence of the incongruently melting addition compounds CH3SiCl3 • Pyridazine, (CH3)2SiCl2 • (Pyridazine)2, (CH3)3SiCl • (Pyridazine)2, CH3SiCl3 • (Pyrazine)2, (CH3)2SiCl2 • (Pyrazine)2 , (CH3)3SiCl • (Pyrazine)2 was proved. By electro-optical measurements of the turbidity point it was proved that the system (CH3)3SiCl- Pyridazine exhibits a miscibility gap which intersects the liquidus curve of the amine. Based on certain approximations it was possible to fit thermodynamic functions to the experimental results to obtain the excess data of mixing of the corresponding systems. These data allow for a more profound understanding of the Lewis-acid base behaviour of the silanes and amines.Chloromethylsilanes, Pyridazine, Pyrazine, Phase Diagrams, Addition Compounds, Thermodynamic Excess Functions