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The Two Expressions of Fundamental Thermodynamics

Author: Adalberto B. M. S. Bassi
April 2006

Abstract
Here, some of the most typical concepts of thermodynamics, namely heat, internal energy, entropy and temperature are used for complementary understanding of the concepts of the enthalpy and energy of Helmholtz and Gibbs. The entropy concept has already been presented by this author, along with some of the concepts of temperature and the energies of [...]


Supercritical Fluid Extraction

Author: Glaucia M. F. Pinto; Jefferson F. Pinto; Protimu Ltda; Isabel C. S. F. Jardim
April 2006

Abstract
This work presents a discussion about the characteristics of supercritical fluid extraction, its operational conditions, a comparison with other extraction techniques and analytical applications of this technique. The text shows that a supercritical fluid can be obtained with different substances if they are above their critical point, the critical temperature and critical pressure, which can [...]


Entropy and Helmholtz’s and Gibbs’ Energies

Author: Adalberto B. M. S. Bassi
November 2005

Abstract
Traditionally, the concept of entropy exists only for equilibria, which then require the same for the Helmholtz’s and Gibbs’ energies, because these are defined from it. As a result, all thermodynamics is restricted to equilibria, although it usually includes quantities classified as mechanical, such as volume and internal energy, which are considered outside the existing [...]


Amount of Substance

Author: Adalberto B. M. S. Bassi
September 2005

Abstract
The amount of substance is one of the four fundamental properties of the thermodynamics in homogeneous media, along with volume, internal energy and entropy. This is a concept taught since high school, but it is not as elementary as it might seem. One aspect not always clear is the fact that it is related to [...]


Amount of Substance and Concentration

Author: João Carlos de Andrade; Rogério Custodio

Abstract
This article presents the definitions of amount of substance, mole and concentration, in addition to the various units accepted by the International System for expressing concentration.
Keywords
molar mass, mole, concentration, molarity, molality, SI
Authors
João Carlos de Andrade
Rogério Custodio
Universidade Estadual de Campinas, Instituto de Química
Translated by
João C. de Andrade
Revised by
Carol H. Collins


Mathematics and Thermodynamics

Author: Adalberto B. M. S. Bassi

Abstract
Mathematics and Thermodynamics seem to be immiscible. Thermodynamicists take their own mathematical path which needs to return more than a century in time to meet the actual science done presently by mathematicians. Mathematicians are usually not interested in thermodynamics, and when they are, their work is not easily understood by thermodynamicists. Although both seem very [...]


Writing Technical and Scientific Texts

Author: Marco-Aurélio De Paoli
July 2004

Abstract
The writing of a didactic text, dissertation, thesis or scientific report or project, requires covering several steps in common, from an appropriate bibliographic search and careful reading of the important papers to be cited, to the writing of the first draft, as the basis for the changes that will result in the final version. Formatting [...]


Determination of Densities of Liquids and Solids

Author: Janaína Cesar; Marco-Aurélio De Paoli; João Carlos de Andrade

Abstract
Many students think that density is simply the result of an arithmetic operation of division between mass and volume of a substance, but this concept is much broader and is related to others, such as compression and packing. For example, the greater the packing of atoms the more dense is the substance. Similarly, the greater [...]


The Closed Box and the Scientific Method

Author: Edvaldo Sabadini

Abstract
This proposed activity involves a playful example of the application of the scientific method. It is based on the discovery of the identity of an object which is inside a closed box and known only by the lecturer. The box remains untouched during the activity, and students are encouraged to find out what is the [...]


Tendencies of the General Chemistry Discipline in Brazil

Author: Janaína César; João Carlos de Andrade; Terezinha Ribeiro Alvim
April 2004

Abstract
As chemistry is a science in constant evolution, the contents of the General Chemistry discipline offered by Brazilian Higher Education Institutions should reflect this fact. Some alternatives to the teaching of general chemistry have been proposed in other countries, but little is known about what is being taught in Brazil, in both the theoretical and [...]