Educacion Quimica最新文献

Conformational analysis is one of the significant subjects in the organic chemistry curriculum. Since this subject may be intricate for some beginner students, a concrete model (an activity) has been devised to explain the conformational concepts with an intriguing and simple method. This model is based on geometric shapes (particularly triangles) in which the revolution of each shape on its axis at the centroid (around its vertices and edges) simulates the rotation about a single bond in a molecule. If we take edges as lower energy (more stable) and vertices as higher energy (less stable), this revolution gives a graph almost identical to the actual conformational energy diagram of that molecule. These shapes can also incorporate into the Newman projections to form a tangible representation of these notations. Most of the participants, who got familiar with these newly modified Newman projections, found them beneficial in enhancing the students’ perception of the basic conformational properties of the molecules. Furthermore, searching for a relevant shape to match the right molecule serves as an activity that in addition to being enjoyable can encourage the students to get engaged with the topic. This model is applicable to a large variety of molecules such as the hydrocarbon, aldehyde and ketone molecules, which can also generalize to more functional groups and compounds.

Trying to integrate knowledge sometimes is very difficult in the experimental sciences, however, the electroplating industry gives us a great opportunity because it allows integrating the knowledge of electrochemistry with the analytical chemistry and hence the use of instruments of varied sophistication in the determination of analytes. The colours of different electrolytes in the bath of electrolysis, in the cited plants, allow using the colorimetric sensor to help plant operator to quantify the degree of electrodeposition of metal of the colored electrolyte. The nickel baths are of extraordinary importance in a electroplating plant, or those requiring to deposit hard copper for the printing roller or small workshops of artisans or jewelers, because nickel coating allows deposit on it, other metals as gold or silver, of greater value, improving the aesthetics value of the obtained piece part and raising their resistance to corrosion and wear. The plant experienced operator, is capable of determining the degree of depletion of electrolyte observing the intensity of the colour to be sent to quantitative analysis, with the aim of adding exactly the amount of nickel salts that need the bath. Using the colorimetric sensor allows this operation efficiently enough, allowing solving quickly, in-situ, the analytical problem.

The fact that sea ice may be a suitable source for fresh water is nothing new; in fact, sailors were aware of this long ago. Nevertheless, the issue that ice does reject the ions of a saline solution is not a well known topic by both novice learners and prospective teachers. This paper describes a practical activity carried out in the regular chemistry training course aimed at teachers-to-be with the objectives of, on the one hand, getting to know the phenomenon of brine rejection and, on the other hand, taking advantage of the utilized experimental design to gain insight into the colligative properties of solutions. This activity might also be adequate for secondary and high school levels.

This work makes a connection between the teaching of stoichiometry, analogies and the conceptual resolution of chemistry problems. A didactic sequence on the topic is drawn up, progressive in difficulty. This sequence, based on analogies, is applied by first year university students. The experience is evaluated by means of a written questionnaire, where, amongst others, Nurrenbern and Pickering's (1987) 2 conceptual stoichiometry items figure (Nurrenbern y Pickering, 1987). The results show only partial understanding of the subject since some difficulties expressed in the bibliography were not overcome. To what extent and under which conditions analogies are helpful in the learning of this subject are discussed.

Through Thomas Lowry's book written in 1915, Historical Introduction to Chemistry, this paper shows how chemistry can be taught from its own history.

Graphics play an important role in data analysis. Boxplots are powerful graphical representation of data that gives an overview and a numerical summary of a data set. In this paper boxplots are used to analyze the periodic trends of main elements. The properties considered are atomic radius, first ionization energy, electron affinity and electronegativity. Boxplots are constructed and metals, nonmetals and metalloids are compared. The results are presented in a manner not explored in chemistry textbooks, pointing out key chemical features visualized through median, quartiles, possible outliers and shape of the distribution. These pictorial representations can show similarities, differences, trends and irregularities among elements, groups and periods, which help better understand their characteristics.

While chemical weapons have been used since the beginning of armed struggles, either for their flammable or toxic properties, it was only during World War I when what is known as “modern” chemical warfare began. July 28 marks the one hundred and one anniversary of the beginning of what is also known as “The Great War”. This conflict created enormous consequences for society at the time, marking a before and after in the history of mankind, as well as being the genesis of modern chemical warfare.

The use of a blog can improve learning of experimental sciences, so a study has been developed. The blog as a strategy allows us to encourage the learning of students and their participation in the course. The study developed contains information about the use of the blog and its positive influence to improve the perception of students towards Chemistry. In quantitative terms, it was found that this tool increases the studentś academic performance thanks to better assimilation of concepts. The sample has been divided into two groups, experimental and control group, the experimental group was involved in the development of the blog, and the control group did not have access to it. In both groups, the subject was developed in the same way, and the lecturer of the two groups was the same. The results showed that the experimental group improved their learning and raised their scores, compared to the control group. Furthermore, the experimental group completed a questionnaire in which they were asked for the usefulness of the blog. The results showed that the majority of students considered the use of blog in a positive way in order to improve the learning and understanding of the subject studied.