A evolução da pós-graduação em química no Brasil

The post-graduate teaching of chemistry in Brazil over the last years is discussed, including comparisons with some other sciences and also experiences in the United States and the United Kingdom. We have also compared the more recent situation with the previous decade, which leads us to a favourable conclusion as to the results obtained in the teaching of post-graduate students in chemistry. Some conclusions and recommendations are made with respect to the near future.

A química na região norte

A historical overview of CHEMISTRY SCIENCE from the beginning of the ESCOLA DE QUÍMICA INDUSTRIAL DO PARÁ in the northern region of Brazil is given. Reports were conducted on graduate and under graduate coursework within research and teaching institutions in each State of the Amazon region. Data collection included teaching, research and industrial activities.

Aplicação de pigmentos de flores no ensino de química

In the present work, the pH dependent colour change of the crude flower extracts is suggested as subject in teaching chemical or acid-base equilibria, visual indicators and some aspects of spectrophotometric concepts and applications. The vegetal species used are commonly found in Brazil, and the extraction methodology proposed is inexpensive and easy to perform in secondary schools and in general chemistry or instrumental undergraduate courses. A bibliographic review about the use of vegetal extracts in chemical education and a discussion of the flower colour are also presented.

The chemistry of peroxynitrite, a biological toxin

Oxyradicals play a tole in several diseases. While for several decades the hydroxyl radical - produced via the Fenton reaction - has been considered the species that initiates oxyradical damage, new findings suggest that much of this damage can be ascribed to peroxynitrite, O=NOO-, formed from the reaction of the superoxide anion with nitrogen monoxide near activated macrophages. The rate constant for the reaction of this reaction has been investigated by flash photolysis and was found to be significantly higher than previously described in the literature, 1.9 x 10(10) M-1s-1. Studies of the isomerization to nitrate resulted in the discovery of a complex between peroxynitrite and its protonated form with a stability constant of 1 x 10(4) M-1. Some of the harmful reaction of peroxynitrous acid have been ascribed to the hydroxyl radical as a product of homolysis of the O-O bond during the conversion to nitrate. Kinetics of the isomerization reaction as a function of pressure show that the activation volume is only +1.5+1.0 ml mol-1, which is inconsistent with homolysis. Instead, an intermediate, possibly a distorted trans-isomer of O=NOOH could be responsible for the harmful reactions of peroxynitrite.

As tecnologias interativas no ensino

The way new interactive computer technologies and the resources of the Internet could be used by teachers and students are explored. The possibilities of some of the Internet resources in chemistry are described.

The use of mini-projects in an undergraduate laboratory course in chemistry

This paper reports the results of a three-year study of the effectiveness of mini-projects in a first year laboratory course in chemistry at a Scottish university. A mini-project is a short, practical problem which requires for its solution the application of the knowledge and skills developed in previously completed set experiments. A number of recommendations have been made about the most appropriate ways of introducing mini-projects into undergraduate laboratory course. The main hypothesis of this survey was concerned with the value of mini-projects in laboratory courses formulated within the context of Information Processing Theory.

The 21st century chemistry journal

Internet publication will radically alter how chemists will publish their research in the next century. In this article, we describe two fundamental changes: enhanced chemical publication which allows chemists to publish materials that cannot be published on paper and end-user customization which allows readers to read articles prepared to meet their specifications. These concepts have been implemented within the Internet Journal of Chemistry, a new journal designed to employ the latest technologies for chemical publications.

Designing an undergraduate laboratory course in general chemistry

From an analysis of a learning model based on the theory of information processing four hypothesis were developed for improving the design of laboratory courses. Three of these hypotheses concerned specific procedures to minimise the load on students' working memories (or working spaces) and the fourth hypothesis was concerned with the value of mini-projects in enhancing meaningful learning of the knowledge and skills underpinning the set experiments. A three-year study of a first year undergraduate chemistry laboratory course at a Scottish university has been carried out to test these four hypotheses. This paper reports the results of the study relevant to the three hypotheses about the burden on students' working spaces. It was predicted from the learning model that the load on students working space should be reduced by appropriate changes to the written instructions and the laboratory organisation and by the introduction of prelab-work and prelab-training in laboratory techniques. It was concluded from research conducted over the three years period that all these hypothesised changes were effective both in reducing the load on students' working spaces and in improving their attitudes to the laboratory course.

A pesquisa como perspectiva de formação continuada do professor de química

The education of a chemistry teacher is not being seen as a specific preparation for the exercise of a professional activity, which differs from the professional activity of a chemist or a chemistry researcher. This happens because in the academic field, mainly in the exact and natural sciences, the idea that knowing a determined subject is enough to be able to teach it, is tacitly accepted. This is, actually, the first condition to be able to be a university professor. There is another necessary condition for competent teaching: to have specific professional knowledege of teaching. I defend that this knowledge can be constitued in the interaction with other professionals in the form of research. Thus, as a chemist constitutes himself through the research in the interaction with other chemists, the teacher develops himself in this professional field in the interaction with other teachers and the permanent attitude of researching.

Molecular mechanics application in inorganic Chemistry

The present paper is a review about basic principles of the molecular mechanics that is the most important tool used in molecular modeling area, and their applications to the calculation of the relative stability and chemical reactivity of organometalic and coordination compounds. We show how molecular mechanics can be successfully applied to a wide variety of inorganic systems.

Química orgânica experimental: integração de teoria, experimento e análise

A new approach for teaching in basic experimental organic chemistry is presented. Experimental work goes on parallel to theoretical lectures leading to an immediate application of theoretical concepts transmitted therein. One day/week is dedicated exclusively to the organic laboratory. Reactions are proposed as problems to be solved; the student has to deduce the structure of the product on the basis of his observations, the analytical data and his mechanistical knowledge. 70 different experiments, divided in 7 thematical chapters, are presented. All experiments require the analysis and discussion of 1H and 13C NMR, IR and UV spectra. Additional questions about each reaction have to be answered by the student in his written report. Laboratory safety is garanteed by the exclusion or substitution of hazardous and toxic reagents. Microscale preparations are adopted in most cases to lower the cost of materials and the amount of waste. Recycling of many reaction products as starting materials in other experiments reduces the need for commercial reagents and allows the execution of longer reaction sequences. Only unexpensive standard laboratory equipment and simple glassware are required. All experiments include instructions for the save treatment or disposal of chemical waste.

Avaliando as aproximações usadas no ensino de Físico-Química

The approaches are part of the everyday of the Physical Chemistry. In many didactic books in the area of Chemistry, the approaches are validated starting from qualitative and not quantitative approaches. We elaborated some examples that allow evaluating the quantitative impact of the approaches, being considered the mistake tolerated for the approximate calculation. The estimate of the error in the approaches should serve as guide to establish the validity of the calculation, which use them. Thus, the shortcut that represents a calculation approached to substitute accurate calculations; it can be used without it loses of quality in the results, besides indicating, as they are valid the adopted criterions.

Fundamentals of beer and hop chemistry

Beer brewing is an intricate process encompassing mixing and further elaboration of four essential raw materials, including barley malt, brewing water, hops and yeast. Particularly hops determine to a great extent typical beer qualities such as bitter taste, hoppy flavour, and foam stability. Conversely, hop-derived bitter acids account for an offending lightstruck flavour, which is formed on exposure of beer to light. These various processes are presented in detail, while due emphasis is placed on state-of-the-art hop technology, which provides brewers with efficient means to control bitterness, foam, and light-stability thereby allowing for the production of beers with consistent quality.