Drop calorimetry of the compounds NbCl5, TaCl5, RbNbCl6, CsNbCl6, RbTaCl6, and CsTaCl6

1989 ◽  
Vol 67 (7) ◽  
pp. 1193-1199 ◽  
Author(s):  
E. E. Shawki ◽  
S. N. Flengas ◽  
D. R. Sadoway
Keyword(s):  
Heat Capacities ◽  
Phase Changes ◽  
Linear Functions ◽  
Drop Calorimetry ◽  
Free Energies ◽  
Pressure Data ◽  
The Third ◽  
Drop Calorimeter ◽  
Third Law ◽  
Solid Compounds

Enthalpy contents for NbCl5, TaCl5, RbNbCl6, CsNbCl6, RbTaCl6, and CsTaCl6 were measured as functions of temperature using a high temperature aluminum block drop calorimeter. It was found that the solid compounds RbNbCl6, CsNbCl6, RbTaCl6, and CsTaCl6 undergo allotropie solid–solid transformations and the enthalpies and entropies associated with these phase changes, as well as from fusion, have been evaluated.Molar heat capacities for the systems investigated are reported as linear functions of temperature.The molar heat capacities for solid and molten NbCl5 or TaCl5 were used together with available vapour pressure data to express enthalpies and free energies of vaporization for these compounds as functions of temperature through the third law calculation method. Keywords: calorimetry, heat capacities, transition enthalpies, niobium compounds, tantalum compounds.

Chemical free energies and the third law of thermodynamics

2006 ◽  
Vol 36 (2) ◽  
pp. 365-396 ◽  
Author(s):  
PATRICK COFFEY
Keyword(s):  
Free Energies ◽  
The Third ◽  
Chemical Significance ◽  
Thermal Measurements ◽  
Limited Applicability ◽  
Third Law Of Thermodynamics ◽  
Third Law ◽  
Human Side ◽  
The 19Th Century

ABSTRACT At the close of the 19th century, it had become clear that determination of the free energy of chemical reactions was the key to understanding chemical affinity. Yet the available methods for obtaining free energies were unreliable and of limited applicability, and there was no known method for determination of free energies from thermal measurements. Walther Nernst's 1906 heat theorem, which later became known as the third law of thermodynamics, would prove to be the key to thermometric determinations of free energies. The paper examines the chemical significance of the third law; earlier attempts by le Chatelier, Lewis, Richards, Haber, and van't Hoff at the problem; and some later clarifications of the third law. The paper then covers the human side of the discovery of the third law, including disputes among Nernst, Lewis, and Richards.

The Second Law of Thermodynamics

2018 ◽  
Author(s):  
Dennis Sherwood ◽  
Paul Dalby
Keyword(s):  
Second Law Of Thermodynamics ◽  
Worked Examples ◽  
Phase Changes ◽  
Second Law ◽  
The Third ◽  
Mathematical Properties ◽  
Third Law Of Thermodynamics ◽  
Third Law ◽  
Definition Of ◽  
Clausius Inequality

The Second Law. The definition of entropy, and its mathematical properties. The Clausius inequality, and the criterion of spontaneity of change in an isolated system. Worked examples of heat flow down a temperature gradient, and the adiabatic expansion of a gas into a vacuum. Combining the First and Second Laws, with worked examples, such as phase changes. Introduction to the Third Law of Thermodynamics. Introduction to T,S diagrams.

Quantification of Biological Resistance: Introducing a Unifying Unit and Scale of Resistance

2018 ◽  
Author(s):  
Rudolf Fullybright
Keyword(s):  
Drug Resistance ◽  
Living Organism ◽  
Pathogen Resistance ◽  
Absolute Quantification ◽  
Biological Resistance ◽  
The Third ◽  
Exact Measurement ◽  
Unit Function ◽  
Third Law ◽  
Accurate Quantification

Accurate quantification of biological resistance has been impossible so far. Among the various forms of biological resistance which exist in nature, pathogen resistance to drugs is a familiar one. However, as in the case of other forms of resistance, accurately quantifying drug resistance in pathogens has been impossible up to now. Here, we introduce a mathematically-defined and uniform procedure for the absolute quantification of biological resistance deployed by any living organism in the biological realm, including and beyond drug resistance in medicine. The scheme introduced makes possible the exact measurement or computation of the extent to which resistance is deployed by any living organism regardless of kingdom and regardless of the mechanism of resistance involved. Furthermore, the Second Law of Resistance indicating that resistance has the potential to increase to infinite levels, and the Third Law of Resistance indicating that resistance comes to an end once interaction stops, the resistance unit function introduced here is fully compatible with both the Second and Third Laws of Resistance.

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