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.

scholarly journals Thermodynamic study of binary mixture of citric acid and tartaric acid

2012 ◽  
Vol 10 (5) ◽  
pp. 1584-1589 ◽  
Author(s):  
Viorica Meltzer ◽  
Elena Pincu
Keyword(s):  
Phase Diagram ◽  
Differential Scanning Calorimetry ◽  
Citric Acid ◽  
Binary Mixture ◽  
Tartaric Acid ◽  
Heat Of Mixing ◽  
Scanning Calorimetry ◽  
Entropy Of Fusion ◽  
Excess Thermodynamic Functions ◽  
Solid Liquid

AbstractThe solid — liquid phase equilibria for binary mixture of citric acid with tartaric acid were measured using differential scanning calorimetry. The phase diagram showed the existence a simple eutectic behavior. The thermal properties of this system as heat of mixing, entropy of fusion and excess thermodynamic functions were computed using enthalpy of fusion values. The composition of eutectic was determined using a Tammann diagram.

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.

scholarly journals Solid–liquid equilibria, physicochemical and microstructural studies of binary organic eutectic alloy: urea + 2-aminobenzothiazole system

2012 ◽  
Vol 10 (10) ◽  
pp. 91-94 ◽  
Author(s):  
Krishna Prasad Sharma ◽  
Pawan Raj Shakya ◽  
Ramananda Rai
Keyword(s):  
Eutectic Alloy ◽  
Thermodynamic Functions ◽  
Roughness Parameter ◽  
Heat Of Mixing ◽  
Organic System ◽  
Thin Glass ◽  
Entropy Of Fusion ◽  
Characteristic Features ◽  
Solid Liquid Interface ◽  
Solid Liquid

Phase diagram of binary organic system of urea (U) with 2-aminobenzothiazole (ABT) shows the formation of a eutectic at 0.350 mole fraction of urea. Growth kinetics of the eutectic and pure components studied by measuring the rate of movement of solid-liquid interface in a thin glass U-tube at different undercoolings (ÄT) suggests the applicability of HilligTurnbull’s equation:  v = u (ÄT) n. The thermodynamic functions such as heat of mixing, entropy of fusion, roughness parameter, interfacial energy and excess thermodynamic functions were calculated from the enthalpy of fusion values, obtained from DSC data. The optical microphotographs of pure and eutectic alloy show their characteristic features. Scientific World, Vol. 10, No. 10, July 2012 p91-94 DOI: http://dx.doi.org/10.3126/sw.v10i10.6871

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.

scholarly journals Bringing naturally-occurring saturated fatty acids into biomedical research

2021 ◽  
Author(s):  
Ke Xue ◽  
Shuyi Lv ◽  
Chunlei Zhu
Keyword(s):  
Fatty Acids ◽  
Liquid Phase ◽  
Biomedical Research ◽  
Low Cost ◽  
Saturated Fatty Acids ◽  
Heat Of Fusion ◽  
Melting Points ◽  
Naturally Occurring ◽  
Large Heat ◽  
Solid Liquid

Naturally-occurring saturated fatty acids (NSFAs) have emerged as a class of promising biomaterials due to their low cost, chemical stability, well-defined melting points, large heat of fusion, reversible solid-liquid phase...

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.

Determination of solid–liquid interfacial energies in the In–Bi–Sn ternary alloy

2008 ◽  
Vol 41 (17) ◽  
pp. 175302 ◽  
Author(s):  
S Akbulut ◽  
Y Ocak ◽  
N Maraşlı ◽  
K Keşlioğlu ◽  
H Kaya ◽  
...  
Keyword(s):  
Ternary Alloy ◽  
Interfacial Energies ◽  
Solid Liquid

scholarly journals Capillary origami: superhydrophobic ribbon surfaces and liquid marbles

2011 ◽  
Vol 2 ◽  
pp. 145-151 ◽  
Author(s):  
Glen McHale ◽  
Michael I Newton ◽  
Neil J Shirtcliffe ◽  
Nicasio R Geraldi
Keyword(s):  
Thin Sheet ◽  
Three Dimensional ◽  
Rigid Surface ◽  
Rigid Substrate ◽  
Elastic Substrate ◽  
Interfacial Tensions ◽  
Liquid Marbles ◽  
Interfacial Energies ◽  
Induced Folding ◽  
Solid Liquid

In the wetting of a solid by a liquid it is often assumed that the substrate is rigid. However, for an elastic substrate the rigidity depends on the cube of its thickness and so reduces rapidly as the substrate becomes thinner as it approaches becoming a thin sheet. In such circumstances, it has been shown that the capillary forces caused by a contacting droplet of a liquid can shape the solid rather than the solid shaping the liquid. A substrate can be bent and folded as a (pinned) droplet evaporates or even instantaneously and spontaneously wrapped on contact with a droplet. When this effect is used to create three dimensional shapes from initially flat sheets, the effect is called capillary origami or droplet wrapping. In this work, we consider how the conditions for the spontaneous, capillary induced, folding of a thin ribbon substrate might be altered by a rigid surface structure that, for a rigid substrate, would be expected to create Cassie–Baxter and Wenzel effects. For smooth thin substrates, droplet wrapping can occur for all liquids, including those for which the Young’s law contact angle (defined by the interfacial tensions) is greater than 90° and which would therefore normally be considered relatively hydrophobic. However, consideration of the balance between bending and interfacial energies suggests that the tendency for droplet wrapping can be suppressed for some liquids by providing the flexible solid surface with a rigid topographic structure. In general, it is known that when a liquid interacts with such a structure it can either fully penetrate the structure (the Wenzel case) or it can bridge between the asperities of the structure (the Cassie–Baxter case). In this report, we show theoretically that droplet wrapping should occur with both types of solid–liquid contact. We also derive a condition for the transition between the Cassie–Baxter and Wenzel type droplet wrapping and relate it to the same transition condition known to apply to superhydrophobic surfaces. The results are given for both droplets being wrapped by thin ribbons and for solid grains encapsulating droplets to form liquid marbles.

Sign in / Sign up

Export Citation Format

Share Document