Studies on the thermodynamics and conductances of molten salts and their mixtures. Part VI. Calorimetric studies of sodium chlorate and its mixtures with sodium nitrate

1968 ◽  
Vol 46 (8) ◽  
pp. 1287-1291 ◽  
Author(s):  
A. N. Campbell ◽  
E. T. van der Kouwe
Keyword(s):  
Sodium Nitrate ◽  
Molten Salts ◽  
Sodium Chlorate ◽  
Heat Of Fusion ◽  
Heat Of Mixing ◽  
Lithium Nitrate ◽  
Entropy Of Fusion ◽  
Direct Experiment ◽  
Calorimetric Studies ◽  
Nitrate System

The following properties have been determined by direct experiment for pure sodium chlorate and its mixtures with sodium nitrate: heat capacity (both solid and liquid) and heat of fusion. From these experimental quantities, the following properties have been derived: entropy of fusion, heat of mixing, and free energy and entropy of mixing. The results have been compared with our previous results for the corresponding lithium chlorate – lithium nitrate system. On the whole, the conclusion is justified that the structure of melts containing lithium chlorate is more complex than that of melts involving sodium chlorate.

Studies on the thermodynamics and conductances of molten salts and their mixtures. Part V. The density, change of volume on fusion, viscosity, and surface tension of sodium chlorate and of its mixtures with sodium nitrate

1968 ◽  
Vol 46 (8) ◽  
pp. 1279-1286 ◽  
Author(s):  
A. N. Campbell ◽  
E. T. van der Kouwe
Keyword(s):  
Activation Energy ◽  
Surface Tension ◽  
Sodium Nitrate ◽  
Molten Salts ◽  
Sodium Chlorate ◽  
Surface Heat ◽  
Lithium Nitrate ◽  
Positive Deviation ◽  
Molten Sodium ◽  
Salt Melts

The densities, viscosities, and surface tensions of molten sodium chlorate, and of molten mixtures of sodium chlorate and sodium nitrate, as well as the change of volume on fusion, have been determined.From the dependence of molar volume on temperature and composition, it appears that the mixing of sodium chlorate and sodium nitrate is a process of dilution rather than of interaction. The viscosity of sodium chlorate is found to be much lower than that of lithium chlorate, a possible indication of greater complexity in the lithium chlorate melt. The activation energy of viscous flow for sodium chlorate is less than that of lithium chlorate. For lithium chlorate – lithium nitrate mixtures, at constant temperature, there is pronounced positive deviation from linearity, when viscosity is plotted against molar composition. For sodium chlorate – sodium nitrate mixtures, the deviation is much less marked though still positive.The surface tension of sodium chlorate is almost identical with those of lithium and potassium chlorates. The surface heat of sodium chlorate is higher than that of lithium chlorate but it still indicates some degree of covalency. The Guggenheim formula and Sokolov's rule have been applied. In contrast to melts of mixtures of lithium chlorate and lithium nitrate, the sodium salt melts would appear to have simpler constituents and to be more ionic in character.

THE BINARY (ANHYDROUS) SYSTEMS NaNO3–LiNO3, LiClO3–NaClO3, LiClO3–LiNO3, NaNO3–NaClO3 AND THE QUATERNARY SYSTEM NaNO3–LiNO3–LiClO3–NaClO3

1962 ◽  
Vol 40 (7) ◽  
pp. 1258-1265 ◽  
Author(s):  
A. N. Campbell ◽  
E. M. Kartzmark ◽  
M. K. Nagarajan
Keyword(s):  
Thermal Analysis ◽  
Sodium Nitrate ◽  
Binary Systems ◽  
Quaternary System ◽  
Sodium Chlorate ◽  
Eutectic Type ◽  
Lithium Nitrate ◽  
Allotropic Transformation ◽  
X Ray ◽  
Invariant Points

The equilibrium diagrams of the systems NaNO3–LiNO3, LiClO3–NaClO3, LiClO3–LiNO3, NaNO3–NaClO3, and NaNO3–LiNO3–LiClO3–NaClO3 have been investigated by thermal analysis and, to some extent, by X-ray powder photography. All the binary systems are of the simple eutectic type, accompanied, in one instance, by considerable solid solubility. The allotropic transformation of sodium nitrate complicates the equilibria involving sodium nitrate somewhat, especially when there is solid solution.The quaternary diagram shows that in the (fused) reaction[Formula: see text]lithium nitrate and sodium chlorate constitute the stable solid pair. The two invariant points of this system are both congruent.

Studies on the thermodynamics and conductances of molten salts and their mixtures. Part VII. The electrical conductance of sodium chlorate and its mixtures with sodium nitrate

1968 ◽  
Vol 46 (8) ◽  
pp. 1293-1296 ◽  
Author(s):  
A. N. Campbell ◽  
E. T. van der Kouwe
Keyword(s):  
Constant Temperature ◽  
Sodium Nitrate ◽  
Molten Salts ◽  
Electrical Conductance ◽  
Sodium Chlorate ◽  
Activation Energies ◽  
Constant Composition ◽  
Temperature Range ◽  
Molten Sodium

The specific and equivalent conductances of molten sodium chlorate and of its mixtures with sodium nitrate have been determined over the temperature range 240–280 °C. The results are treated as temperature functions at constant composition and as composition functions at constant temperature. From these data, the activation energies of conductance have been derived. The results have been compared with various theoretical equations and the conclusion is made that, while melts containing lithium chlorate may be associated or complexed in some way, the sodium chlorate melts show less of such a structure and are more ionic.

Some thermodynamic aspects of organic eutectic in a monotectic type system

1987 ◽  
Vol 65 (11) ◽  
pp. 2639-2642 ◽  
Author(s):  
U. S. Rai ◽  
O. P. Singh ◽  
Narsingh B. Singh
Keyword(s):  
Cluster Formation ◽  
Type System ◽  
Heat Of Fusion ◽  
Heat Of Mixing ◽  
Present System ◽  
Entropy Of Fusion ◽  
Interfacial Energies ◽  
Organic Eutectic ◽  
Solidification Morphology ◽  
Solid Liquid

Phase diagram and heat of fusion of succinonitrile–phenanthrene system have been studied. Heat of mixing, entropy of fusion, and excess thermodynamic functions such as hE, sE, and gE have also been calculated. The results have been explained on the basis of cluster formation and the interactions among the components forming the eutectic melt. Solid–liquid and liquid–liquid interfacial energies calculated from the heats of fusion of the pure components suggest the validity of Cahn wetting condition and predict the monotectic solidification morphology in the present system.

Some Physicochemical Studies on Organic Eutectics and Molecular Complex: Urea – p-nitrophenol System

1999 ◽  
Vol 14 (4) ◽  
pp. 1299-1305 ◽  
Author(s):  
U. S. Rai ◽  
R. N. Rai
Keyword(s):  
Molecular Complex ◽  
Roughness Parameter ◽  
Heat Of Fusion ◽  
Heat Of Mixing ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Entropy Of Fusion ◽  
Composition Curve ◽  
Characteristic Features ◽  
Dsc Method

The phase diagram of urea–p-nitrophenol system, in the form of a temperature-composition curve, shows the formation of a 1: 1 molecular complex surrounded by two eutectics containing 0.216 and 0.777 mole fraction of p-nitrophenol. Data on growth velocity (v), obtained by measuring the rate of movement of the interface at different undercoolings (ΔT), suggest that they obey the Hillig–Turnbull equation, i.e., v = u (ΔT)n, where u and n are constants depending on the nature of materials involved. From the heat of fusion values, determined by the differential scanning calorimetry (DSC) method, heat of mixing, entropy of fusion, roughness parameter, interfacial energy, radius of the critical nucleus, and the excess thermodynamic functions were calculated. While the x-ray diffraction data show that the eutectics are not mechanical mixtures of the components under investigation, the microstructural investigations give their characteristic features.

Fundamentals

2020 ◽  
pp. 41-77
Author(s):  
Joel Bernstein
Keyword(s):  
Fusion Rule ◽  
Crystal Form ◽  
Crystal Habit ◽  
Heat Of Fusion ◽  
Transition Rule ◽  
Phase Rule ◽  
Entropy Of Fusion ◽  
Thermodynamic Relationships ◽  
Heat Of Transition ◽  
Definition Of

The physical and structural fundamentals of polymorphism are introduced, including a review of the phase rule and the thermodynamic relations in polymorphs. The latter are used to introduce energy–temperature diagrams, leading to the definition of the concepts enantiotropism and monotropism describing the thermodynamic relationships between and among polymorphs with appropriate examples. The alternate representation of phase diagram in terms of pressure and temperature is also presented. These lead to a number of rules regarding the relationships between polymorphs and ways to understand and predict some important physical properties: the heat-of-transition rule, the heat-of-fusion rule, the entropy-of-fusion rule, the heat-capacity rule, the density rule, and the infrared rule. Structural aspects include the distinction between crystal form and crystal habit and methods for characterizing and comparing structures in polymorphic systems. Current developments are discussed that deal with the ramifications of nanoscale situations on structural concepts and thermodynamic relationships.

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