Field amount of substance and modelling in a reaction system with diffusion

Orientador: Adalberto Bono Maurizio Sacchi BassiTese (doutorado) - Universidade Estadual de Campinas, Instituto de QuímicaResumo: A Termodinâmica dos meios contínuos é uma teoria de campos, que utiliza as equações de balanço de massa, energia, momento linear, momento angular, a desigualdade de entropia e as equações constitutivas para descrever um sistema. Nesta teoria pode-se trabalhar com um único constituinte ou com uma mistura e, também, em um meio com ou sem reação química. Esta teoria foi desenvolvida por matemáticos e é muito utilizada por engenheiros. Com o intuito de aproximá-la dos químicos, neste trabalho é utilizado o balanço de quantidade de matéria ao invés do balanço de massa. Além disso, neste trabalho é considerado que o sistema apresente múltiplas temperaturas, ou seja, não há um único campo temperatura para o sistema, mas um campo temperatura para cada constituinte. Portanto, o objetivo deste trabalho é descrever um sistema com reação química, difusão e múltiplas temperaturas, utilizando o balanço de quantidade de matéria. Assim, para o sistema em questão foram obtidas as expressões para a produção e o fluxo de entropiaAbstract: The Thermodynamics of continuous media is a theory of fields, which uses the balance equations of mass, energy, momentum, angular momentum, entropy inequality and constitutive equations to describe a system. This theory enables us to work with a single constituent or a mixture and in a medium with or without chemical reaction. This theory was developed by mathematicians and have been widely applied by engineers. In order to foster the application of this theory by chemistry professionals, this research applies the theory by adapting the formula, using the substance balance rather than the mass balance. Moreover, the research assumes that the system presents multiple temperatures, ie there is not a single field for the system temperature but a temperature field for each constituent. Therefore, the goal of this research is to describe a system with chemical reaction, diffusion and multiple temperatures, using the amount of substance balance. Thus, for the system in question were obtained expressions for the production and entropy flowDoutoradoFísico-QuímicaDoutor em Ciência

Conditions for thermodynamic equilibrium: the function availability

The thermodynamic equilibrium is a state defined by conditions which depend upon some characteristics of the system. It requires thermal, mechanical, chemical and phase equilibrium. Continuum thermodynamics, its radical restriction usually called homogeneous processes thermodynamics, as well as the classical thermodynamic science of reversible processes, each of them defines equilibrium in a differing way. But these definitions lead to the same physical contents.16016

The chemical amount in classical sciences

The chemical amount values vary in a discrete or continuous form, depending on the approach used to describe the system. In classical sciences, the chemical amount is a property of the macroscopic system and, like any other property of the system, it varies continuously. This is neither inconsistent with the concept of indivisible particles forming the system, nor a mere approximation, but it is a sound concept which enables the use of differential calculus, for instance, in chemical thermodynamics. It is shown that the fundamental laws of chemistry are absolutely compatible to the continuous concept of the chemical amount.1961196

Critical comparison of thermodynamics textbooks

Orientador: Adalberto Bono Maurizio Sacci BassiDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de QuimicaResumo: A termodinâmica clássica é utilizada, por muitos professores e autores, exclusivamente como um instrumento para a solução de problemas. Por isto, não costuma ser feita uma discussão aprofundada sobre seus conceitos, sobre suas equações matemáticas, ou sobre a limitação teórica da termodinâmica. Este trabalho é realizado dentro deste contexto. O intuito do trabalho é o de analisar e comparar livros didáticos de termodinâmica clássica, na definição dos conceitos e no tratamento matemático utilizado. Verificar se existe uma única termodinâmica clássica, ou se as idéias mais fundamentais apresentadas dependem fortemente do enfoque do autor, ou do que este quer mostrar. Foram escolhidos sete livros didáticos bem conhecidos (Atkins, Callen, Guggenheim, Levine, McQuarrie et al., Moran et al. e Sonntag et al.) e, além destes autores, outros também foram utilizados, mas de forma mais específica. Supondo-se que os autores mantenham coerência interna nos seus respectivos livros, eventuais incoerências entre os autores, em conceitos derivados dos alicerces da termodinâmica, seriam apenas necessárias conseqüências de incoerências mais fundamentais. Por isto, não se considera que restringir a comparação aos conceitos fundamentais implique numa perda de abrangência, em relação aos objetivos antes colocados. O trabalho está dividido em seis seções, cada uma delas subdividida em três partes: colocações feitas por cada um dos sete autores; comparação entre os autores; e eventual apresentação de conceitos preferidos por outros autores. Há, ainda, a conclusão, que contém uma discussão mais aprofundada sobre alguns tópicos específicos e a introduçãoAbstract: Classical thermodynamics is used, by many professors and authors, exclusively as an instrument for solving problems. Because of that, concepts, mathematical foundations and even thermodynamics limitations as a theorethical model aren¿t often discussed. This piece develops within this context. The aim of this paper is to analyze and compare classical thermodynamics textbooks in regard to concepts presented and mathematical models applied. Also, to verify if there is a consensual classical thermodynamics or if the ideas presented vary among the authors. Seven well-known pieces were chosen (Atkins, Callen, Guggenheim, Levine, McQuarrie et al., Moran et al. e Sonntag et al.) and, on top of these textbooks, others were used specifically. Supposing the authors are coherent within their own writings, inconsistencies that might be found among the authors could be the consequence of divergencies regarding the basis of thermodynamics. Consequently, narrowing down the analysis exclusively to basic concepts is not considered superficial. The work is divided into six sections, each one with three parts: presentation of each author¿s concept; comparison among the authors; and eventually, concepts adopted by other authors. There is also a conclusion covering an in-deep discussion of some topics presented, as well as the introduction of the paperMestradoFísico-QuímicaMestre em Químic

A primeira lei da termodinâmica dos processos homogêneos

Thermodynamics of homogeneous processes, which corresponds to the very special situation in thermodynamics of continuous media, is used to discuss the first law. An important part of this work is the exposition of some typical mathematical errors, frequently found in the traditional presentation of thermodynamics. The concepts of state and process functions are discussed, as well as reverse and reversible processes, temporality and its implications on thermodynamics, energy reservoirs and symmetry. Our proposal is to present the first law by using a time dependent viewpoint coherent with mechanics and the foundations of that viewpoint

A quantidade de matéria nas ciências clássicas

The chemical amount values vary in a discrete or continuous form, depending on the approach used to describe the system. In classical sciences, the chemical amount is a property of the macroscopic system and, like any other property of the system, it varies continuously. This is neither inconsistent with the concept of indivisible particles forming the system, nor a mere approximation, but it is a sound concept which enables the use of differential calculus, for instance, in chemical thermodynamics. It is shown that the fundamental laws of chemistry are absolutely compatible to the continuous concept of the chemical amount

Condições de equilíbrio termodinâmico: a função disponibilidade

The thermodynamic equilibrium is a state defined by conditions which depend upon some characteristics of the system. It requires thermal, mechanical, chemical and phase equilibrium. Continuum thermodynamics, its radical restriction usually called homogeneous processes thermodynamics, as well as the classical thermodynamic science of reversible processes, each of them defines equilibrium in a differing way. But these definitions lead to the same physical contents

The first law of homogeneous processes thermodynamics

Thermodynamics of homogeneous processes, which corresponds to the very special situation in thermodynamics of continuous media, is used to discuss the first law. An important part of this work is the exposition of some typical mathematical errors, frequently found in the traditional presentation of thermodynamics. The concepts of state and process functions are discussed, as well as reverse and reversible processes, temporality and its implications on thermodynamics, energy reservoirs and symmetry. Our proposal is to present the first law by using a time dependent viewpoint coherent with mechanics and the foundations of that viewpoint.52252