scholarly journals On the ambiguity of an ideal gas entropy concept

2020 ◽  
Vol 22 (4) ◽  
pp. 32-42
Author(s):  
V. G. Kiselev
Keyword(s):  
Critical Analysis ◽  
Ideal Gas ◽  
Absolute Temperature ◽  
Carnot Cycle ◽  
Perfect Gas ◽  
Reversible Process ◽  
Thermodynamic Potentials ◽  
Adiabatic Processes ◽  
Isothermal Processes

Based on a critical analysis of the existing characteristics of an ideal gas and the theory of thermodynamic potentials, the article considers its new model, which includes the presence of an ideal gas in addition to kinetic energy of potential (chemical) energy, in the framework of which the isothermal and adiabatic processes in it are studied both reversible and irreversible, in terms of changes in the entropy of the system in question, observed in case. In addition, a critical analysis was made of the process of introducing the concept of entropy by R. Clausius, as a result of which the main requirements for entropy were established, the changes of which are observed in isothermal and adiabatic quasistatic processes, in particular, it was revealed that if in isothermal processes involving one in a perfect gas, the entropy ST is uniquely characterized by the value , regardless of whether the process is reversible or not, then when the adiabatic processes occur, the only requirement made of them is the condition of mutual destruction adiabats in this Carnot cycle. As a result of this circumstance, in fact, in thermodynamics various “adiabatic” entropies are used, namely; const SA = const R ln V  и  C V ln T , and in addition, as established in this paper, CV, which leads, despite the mathematically perfect introduction of the concept of entropy for the Carnot cycle, to the impossibility of its unambiguous interpretation and, therefore, the determination of its physicochemical meaning even for perfect gas. A new concept is introduced in the work: “total” entropy of an ideal gas SS = R ln V + C V , satisfying the criteria of R. Clausius, on the basis of which it was established that this type of entropy multiplied by the absolute temperature characterizes a certain level of potential energy of the system, which can besuccessively converted to work in an isothermal reversible process, with the supply of an appropriate amount of heat, and in the adiabatic reversible process under consideration.

scholarly journals Studies in brownian movement.— II. The determination of avogadro's number from observations on bacteria (cocci)

1923 ◽  
Vol 104 (728) ◽  
pp. 655-667 ◽  
Keyword(s):  
Absolute Temperature ◽  
Spherical Particles ◽  
Brownian Movement ◽  
Perfect Gas ◽  
Liquid Media ◽  
Avogadro’S Number ◽  
Fluid State ◽  
Usual Form ◽  
The Mean

1. The Brownian movement is now definitely accepted as a manifestation of the motion of molecules in the fluid state. Its mathematical theory, first given by Einstein, has been verified by Perrin and his co-workersf for liquid media, by Harvey Fletcher, Eyring and others for gases. The most usual form of the equation of Brownian movement is l 2͞ = RT/πN ηa t , in which R is the gas constant and N the number of molecules per gram-molecule of a perfect gas, T the absolute temperature and η the viscosity of the medium which suspends spherical particles exhibiting the movement, a the radius of such a particle and l 2͞ the mean square of its displacement in a time t , this displacement being wholly due to the Brownian movement.

scholarly journals Regarding the application limitations of the Carnot, s theorem

2019 ◽  
Vol 21 (3) ◽  
pp. 32-45
Author(s):  
V. G. Kiselev
Keyword(s):  
Correction Term ◽  
Heat Engine ◽  
Thermodynamic Characteristics ◽  
Ideal Gas ◽  
Working Fluid ◽  
Cyclic Process ◽  
Carnot Cycle ◽  
Real Gas ◽  
Main Research ◽  
Thermodynamic Potentials

The purpose of this article is to perform a comparative study of a reversible heat engine with an ideal or real gas as a working fluid and to determine the change in its efficiency depending on the thermodynamic characteristics of the working fluid. The main research method is the method of thermodynamic potentials, based primarily on the analysis of changes in the free and internal energy of an ideal and real gas in a cyclic process. The theory of thermodynamic potentials is used to consider the Carnot quasistatic heat engine. A comparative analysis of its operation is carried out, for a cycle with both an ideal and a real gas as a working fluid. The possibility of analyzing cyclic processes occurring in heat engines using the method of thermodynamic potentials has been identified and substantiated. The study has shown that the existing formulation of the Carnot’s theorem is valid only for ideal gas as a working fluid. Based on the work carried out, the Carnot’s theorem in the general case can be formulated, for example, as follows: the efficiency of the heat engine ηr, when it operates at the reversible Carnot cycle with real gas as a working fluid, is determined by the following expression:hr= 1 - TB /TA + ε,where TA and TB are the temperatures of the upper and lower isotherms of the Carnot cycle, respectively; ε is the correction term (positive or negative), depending on the thermodynamic properties of a real gas, which tends to zero as the properties of a real gas approach the properties of an ideal gas.

scholarly journals A History of Thermodynamics: The Missing Manual

Entropy ◽  
2020 ◽  
Vol 22 (1) ◽  
pp. 77 ◽  
Author(s):  
Wayne M. Saslow
Keyword(s):  
Thermodynamic Temperature ◽  
Ideal Gas ◽  
Absolute Temperature ◽  
Carnot Cycle ◽  
State Function ◽  
Gas Temperature ◽  
Conservation Of Energy ◽  
Engine Efficiency ◽  
Heat Conservation ◽  
History Of

We present a history of thermodynamics. Part 1 discusses definitions, a pre-history of heat and temperature, and steam engine efficiency, which motivated thermodynamics. Part 2 considers in detail three heat conservation-based foundational papers by Carnot, Clapeyron, and Thomson. For a reversible Carnot cycle operating between thermal reservoirs with Celsius temperatures t and t + d t , heat Q from the hot reservoir, and net work W, Clapeyron derived W / Q = d t / C ( t ) , with C ( t ) material-independent. Thomson used μ = 1 / C ( t ) to define an absolute temperature but, unaware that an additional criterion was needed, he first proposed a logarithmic function of the ideal gas temperature T g . Part 3, following a discussion of conservation of energy, considers in detail a number of energy conservation-based papers by Clausius and Thomson. As noted by Gibbs, in 1850, Clausius established the first modern form of thermodynamics, followed by Thomson’s 1851 rephrasing of what he called the Second Law. In 1854, Clausius theoretically established for a simple Carnot cycle the condition Q 1 / T 1 + Q 2 / T 2 = 0 . He generalized it to ∑ i Q i / T g , i = 0 , and then ∮ d Q / T g = 0 . This both implied a new thermodynamic state function and, with appropriate integration factor 1 / T , the thermodynamic temperature. In 1865, Clausius named this new state function the entropy S.

scholarly journals CARNOT AND PHILIPS HEAT ENGINES IN VIEW OF THE THEORY OF THERMODYNAMIC POTENTIALS

2019 ◽  
Vol 20 (9-10) ◽  
pp. 154-165 ◽  
Author(s):  
V. G. Kiselev
Keyword(s):  
Traditional Approach ◽  
Potential Method ◽  
Ideal Gas ◽  
Absolute Temperature ◽  
Chemical Thermodynamics ◽  
Heat Engines ◽  
Thermodynamic Potentials ◽  
Cyclic Processes ◽  
New Research ◽  
Direct Use

A study has been made of the Philips and Carnot cycles based on the modernized physicochemical model of "ideal gas", which utilizes the theory of thermodynamic potentials and assumes the presence of chemical energy. The feasibility study of the Phillips and Carnot heat engines using the thermodynamic potential method is substantiated by plotting the diagrams of the dependence of the internal energy and Helmholtz energy on the absolute temperature and their comparison with the usual pressure-volume diagrams. This method is compared with traditional approach to analysis of cyclic processes. Based on the analysis carried out, the results are similar to those obtained in the study of these processes in the traditional way. On the other hand, the use of new research methods has a significant advantage, since it allows direct use of the activity of the substance (gas) and the entire arsenal of chemical thermodynamics for the analysis of cyclic processes, for example, in the thermal machines of Philips and Carnot.

scholarly journals The Carnot Cycle, Reversibility and Entropy

Entropy ◽  
2021 ◽  
Vol 23 (7) ◽  
pp. 810
Author(s):  
David Sands
Keyword(s):  
Irreversible Process ◽  
Entropy Change ◽  
External Pressure ◽  
Step Change ◽  
Equilibrium States ◽  
Rate Equations ◽  
Carnot Cycle ◽  
Work Processes ◽  
Reversible Process ◽  
External Conditions

The Carnot cycle and the attendant notions of reversibility and entropy are examined. It is shown how the modern view of these concepts still corresponds to the ideas Clausius laid down in the nineteenth century. As such, they reflect the outmoded idea, current at the time, that heat is motion. It is shown how this view of heat led Clausius to develop the entropy of a body based on the work that could be performed in a reversible process rather than the work that is actually performed in an irreversible process. In consequence, Clausius built into entropy a conflict with energy conservation, which is concerned with actual changes in energy. In this paper, reversibility and irreversibility are investigated by means of a macroscopic formulation of internal mechanisms of damping based on rate equations for the distribution of energy within a gas. It is shown that work processes involving a step change in external pressure, however small, are intrinsically irreversible. However, under idealised conditions of zero damping the gas inside a piston expands and traces out a trajectory through the space of equilibrium states. Therefore, the entropy change due to heat flow from the reservoir matches the entropy change of the equilibrium states. This trajectory can be traced out in reverse as the piston reverses direction, but if the external conditions are adjusted appropriately, the gas can be made to trace out a Carnot cycle in P-V space. The cycle is dynamic as opposed to quasi-static as the piston has kinetic energy equal in difference to the work performed internally and externally.

Research progress in electroanalytical techniques for determination of antimalarial drugs in pharmaceutical and biological samples

RSC Advances ◽  
2016 ◽  
Vol 6 (62) ◽  
pp. 57580-57602 ◽  
Author(s):  
Neeta Thapliyal ◽  
Tirivashe E. Chiwunze ◽  
Rajshekhar Karpoormath ◽  
Rajendra N. Goyal ◽  
Harun Patel ◽  
...  
Keyword(s):  
Biological Samples ◽  
Critical Analysis ◽  
Pharmaceutical Formulations ◽  
Antimalarial Drugs ◽  
Research Progress ◽  
Electroanalytical Methods ◽  
Biological Matrices

The review focusses on the role of electroanalytical methods for determination of antimalarial drugs in biological matrices and pharmaceutical formulations with a critical analysis of published voltammetric and potentiometric methods.

scholarly journals Metaphysical Anthropocentrism, Limitrophy, and Responsibility: An Explication of the Subject of Animal Rights

2018 ◽  
Vol 21 ◽  
pp. 1-29
Author(s):  
Jan-Harm De Villiers
Keyword(s):  
Animal Rights ◽  
Critical Analysis ◽  
De Novo ◽  
Social Regulation ◽  
Traditional Model ◽  
Conceptual Level ◽  
The Subject ◽  
Metaphysical Tradition ◽  
Point Of Departure

This article undertakes a critical analysis of subjectivity and exposes the metaphysical and anthropocentric quasi-transcendental conditions that give rise to the construct(ion) of the Subject. I locate a critical moment for the metaphysical Subject in the work of Martin Heidegger which, whilst sadly not sustained in his later writings, provides a point of departure for an examination of the significance that animality plays in the metaphysical tradition and its constitutive relation to the construct of subjectivity. I discern this relation to be violent and sacrificial and draw on Jacques Derrida's nonanthropocentric ethics against the background of Drucilla Cornell's ethical reading of deconstruction to construct a critique of approaches that assimilate animals to the traditional model of subjectivity in order to represent their identity and interests in the legal paradigm. The main argument that I seek to advance is that such an approach paradoxically re-constructs the classical humanist subject of metaphysics and re-establishes the subject-centred system that silences the call of the animal Other, thereby solidifying and extending the legitimacy of a discourse and mode of social regulation that is fundamentally anthropocentric. I examine how we can address, incapacitate and move beyond this schemata of power through a rigorous deconstruction of the partitions that institute the Subject and how deconstruction clears a space for a de novo determination of the animal "subject" that can proceed from different sites of nonanthropocentric interruption. What follows is a call to refuse the mechanical utilisation of traditional legal constructs and I argue in favour of an approach to the question of the animal (in law) that identifies and challenges anthropocentrism as its critical target. I ultimately propose a critical engagement with the underlying metaphysical support of animal rights at a conceptual level, rather than simply utilising the law pragmatically as an instrument of immediate resolution.    

Determination of Women Collective Farming Groups in Kerala towards Attaining Goals: A Critical Analysis

2021 ◽  
pp. 82-88
Author(s):  
T. Shahlas Binth ◽  
Basavaraj Hulagur ◽  
S. B. goudappa ◽  
Jagrati B. Deshmanya
Keyword(s):  
Critical Analysis ◽  
Collective Farming

Thermoelasticity

1997 ◽  
Author(s):  
Burak Erman ◽  
James E. Mark
Keyword(s):  
Equation Of State ◽  
Elastic Deformation ◽  
Additional Assumption ◽  
Polymer Network ◽  
Ideal Gas ◽  
Absolute Temperature ◽  
Constant Volume ◽  
Conformational Energy ◽  
Network Chain ◽  
Constant Deformation

The important postulate that intermolecular interactions are independent of extent of deformation leads directly to the conclusion that such interactions cannot contribute to an energy of elastic deformation ΔEel at constant volume. In the earliest theories of rubberlike elasticity, it was additionally assumed that, intramolecular contributions to ΔEel were likewise nil. In this idealization that the total ΔEel is zero, the elastic retractive force exhibited by a deformed polymer network would be entirely entropic in origin. At the molecular level, this would correspond, of course, to assuming all configurations of a network chain to be of exactly the same conformational energy and thus the average configuration to be independent of temperature. Under these circumstances, the dependence of stress on temperature is strikingly simple, as shown, for example, by the equation . . . f* = υkT/V (〈r2〉i/〈r2〉0)(α – α-2) . . . . . . (9.1) . . . that characterizes a polymer network in elongation where, it should be recalled, 〈r2〉i3/2 is proportional to the volume of the network. This additional assumption that 〈r2〉0 is independent of temperature would lead to the prediction that the elastic stress determined at constant volume and elongation α is directly proportional to the absolute temperature. Such network chains would be akin to the particles of an ideal gas, which would obey the equation of state p = nRT(1/V) and thus exhibit a pressure at constant deformation (1/V) likewise directly proportional to the temperature.

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