Educacion Quimica最新文献

Louis Édouard Grimaux (1835–1900), a French physician and pharmacist, devoted most of his efforts to the synthesis and properties of a large variety of organic compounds, the ureic series, alkaloids, nitrogen cyclic compounds, aromatic aldehydes, etc. He synthesized citric acid and a variety of colloids, albumins, and carbon hydrates. His open support of the innocence of Alfred Dreyfus led to his dismissal from the École Polytechnique, then under the rule of the Ministry of War.

This paper seeks to understand the institutional and cognitive features of the development of chemistry as a discipline in Latin America. With this purpose, a comparative study between Argentina, Colombia and Mexico has been carried out. We show that the history of chemistry in these countries can be divided into 3 stages: first, the institutionalization of teaching as a distinct discipline by a creation of a university chemical degree and the differentiation from pharmacology; second, the creation of national chemical organization; and finally, the professionalization of chemical research. The work aims to show how the development of chemistry in these countries involved a distinct sequence in its institutionalization in the teaching, practice and research.

In this century, chemists find themselves with a new challenge. They need to efficiently generate materials to maintain quality of life, but they have to do so reducing the negative effects on the environment and human health. Teaching green chemistry is fundamental to promote future scientists who can create safely and efficiently non-toxic products and processes in the way for a sustainable future. The use of a multicomponent reaction, as the Passerini reaction, for the generation of new molecules as drug candidates, is described here as an experiment for undergraduate organic chemistry laboratory. It is a fast, efficient and simple process which generates a complex product using simple reactants in one step. Different metrics were determined in order to measure how environmentally friendly this reaction is, in the conditions tested. The student will be able to discuss: green chemistry, development of bioactive molecules, diversity-oriented synthesis, multicomponent reactions, and chemistry in aqueous solution.

Learning chemistry at university level has become every day a less attractive field for first year students. They have little interest in the subject and they are prone to fail. In that regard, new methodologies based on teaching innovation have become an ally for students. In this work, a teaching innovation case is presented using socrative.com platform. The platform possess a friendly environment and has been designed to have an immediately feedback of students’ progress when they use their own mobile devices. The results show that students rapidly adopt the platform since they are digital natives. They are prone to answer the chemical question through their touch devices due to they are able to remain anonymous. Thus, they do not have to solve exercises on the board. They recognize that the platform helped them pass the course and get excited about the fact extend this to other subjects.

Since its introduction, pedagogical content knowledge (PCK) has been widely written about in the science education research literature. It has served as an alluring concept amongst many of the discussions on the teaching and learning of science. This paper reviews and draws together empirical research on a specific PCK lens, consisting of two tools: a Content Representation (CoRe) and Pedagogical and Professional Experiences Repertoires (PaP-eRs). Both tools were originally developed by Loughran et al. (2006) and have since been used by a variety of educational researchers and practitioners within their own contexts. This paper seeks to present how CoRes and PaP-eRs have helped conceptualise and advance PCK research, including the impact this has had on the professional practice of teachers. This paper, in so doing, also demonstrates how this PCK lens can facilitate effective teaching and learning in science education.

17 original crystals of [Λ-dinitrobis(ethylenediamine)cobalt]X complexes from the Alfred Werner collection of original samples of the University of Zurich were studied by single crystal X-ray diffraction revealing that the complexes with X = Cl, Br can undergo spontaneous chiral resolution upon crystallization. The main focus of this article was the chiral [Λ- and Δ-dinitrobis(ethylenediamine)cobalt]Cl complexes, which crystallize from racemic solution in the space group P 2₁ mainly as synthetical twins enriched in one enantiomer, but to a small extent also as pure enantiomorphs. The twinning effect was recognized and correctly described by PhD student Richard Hessen of the Alfred Werner group (PhD thesis 1914). Richard Hessen eventually resolved the [Δ- and Λ-dinitrobis(ethylenediamine)cobalt]Cl complex by the conglomerate salt resolution method. Based on the availability of the pure [Δ- or Λ-dinitrobis(ethylenediamine)cobalt]Cl complex, he carried out seeding experiments, which proved that the [Δ- and Λ-dinitrobis(ethylenediamine)cobalt]Cl complexes can be enriched to a great extent in one enantiomer by spontaneous chiral resolution. Already in the period of time from 1900 to 1904, various PhD students of Alfred Werner's group (Adolf Grün, Edith Humphrey, Ernst Zinggeler, Heinrich Schwarz, and Paul Larisch) prepared the [Δ- or Λ-dinitrobis(ethylenediamine)cobalt]Cl complex. Adolf Grün and Edith Humphrey have prepared enantiomerically enriched and rarely also enantiomorphic crystals of the [Λ- or Δ-dinitrobis(ethylenediamine)cobalt]Cl complex and could have separated crystals by manual crystal picking. Admittedly due to the crystal habits this would have been a difficult endeavour, but this ‘Louis Pasteur method’ was apparently not taken into consideration. Still in a cautiously sounding note one could state that Alfred Werner and his group had missed by this omission the opportunity for spontaneous chiral resolution of the [Δ- and Λ-dinitrobis(ethylenediamine)cobalt]Cl complexes in the period of time from 1900 to 1904. In addition, making this early chiral resolution story even more incredible, we found that Heinrich Schwarz and Paul Larisch applied in these early days of coordination chemistry the S-(D-,d-)camphorsulfonate anion to achieve the separation of the cis- and trans-isomers of the [dinitrobis(ethylenediamine)cobalt] complexes. They did not approach the potentially possible chiral resolution of the [cis-dinitrobis(ethylenediamine)cobalt]⁺ cation. But based on their synthetic procedure they did indeed accomplish chiral resolution of the cis-isomer and prepared eventually a series of the chiral [cis-,Λ-dinitrobis(ethylenediamine)cobalt]X salts; however all this was in an unintentional manner.

The Langmuir isotherm is one of the most powerful and descriptive models for the adsorption process. Applied to fluid interfaces, in conjunction with Gibbs adsorption equation, it provides a meaningful physical description of surface tension on a molecular level. The resulting equation could be expressed as a function of volumetric phase composition or surface phase composition to calculate critical micelle concentration of surfactants in solution, as well as the adsorption and aggregation energies in a direct way, avoiding the use of empirical constants. In this work, the multiple advantages of the Langmuir model and its application to the calculation of these properties are presented.

The presence of a feature of contemporary innovations in science education using the concept “Chemistry in Context” from the approach Science, Technology and Society applied to this teaching is analyzed. This is a sub-study from a larger one about innovative practices, its identification and characterization. A methodology based on 6 semi-structured interviews to innovative teachers selected from a group of 29 was used. Triangulation between coders was done and a report was generated. Innovative practices with a varied range of activities to contextualize the teaching of chemistry are identified. Some of them are real problems of research focused on the daily basis. Their innovative nature and permanence and the future of these practices at schools are valued.

The 9 bottle problem is a classical lab job in high school and college chemistry.

In solving this chemical “crossword” puzzle, students will be forced to integrate the knowledge acquired on a great variety of items such as solubility and colors of common inorganic precipitates, the possible evolution of gases, acid-base properties of salts, formation of metal-ion complexes, acid-base reactions, and oxidation-reduction reactions, including the influence of pH on them.

A free copy of the program and the teacher guide, in Spanish, are available from the authors upon request.