ISSN 0187-893X       ISSNE 1870-8404
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Fotoprocesos en la ense˜nanza de la química. Experimentos clave para conceptos básicos

Michael Walter Tausch, Nico Meuter, Sebastian Spinnen   
Debido a los «cinco grandes» retos del sigloXXI en relación con los términos de energía, alimentos, agua, movilidad y clima, la humanidad tiene que sustituir la energía de combustibles fósiles por las energías renovables paso a paso. Entre ellas, la energía solar es, sin ninguna duda, la más abundante y limpia. Esta es una razón importante, pero no la única, para la inclusión de los fotoprocesos en la enseñanza de la química.

Investigation in Analytical Chemistry applied to Nutrition as a tool in teaching

Rodrigo José Vargas, Dulce G. Saldaña, Lorena López-Donado   
Research is one of the necessary elements to build up knowledge; for this reason, the career of nutrition at Mariano Galvez University has implemented research as an important component of the course of analytical chemistry. During this process, the impact of scientific involvement is evaluated as part of a regular course and it allows students to develop a research as a product of their imagination and curiosity.

Proposed class experimental using expanded perlite modified with orthophenanthroline in removal of eriochrome black t in complexing titrimetry waste

Janiele Mayara Ferreira de Almeida, Sheila Pricila Marques Cabral de Souza, Isabel do Nascimento Silva, Nedja Suely Fernandes   
In this paper, an approach to the removal of the eriochrome black T in an actual effluent (generated from the test to determine the water hardness by complexometric titration) using perlite modified with orthophenanthroline by the adsorption technique is proposed. A preliminary assessment of the removal of eriochrome black T in a synthetic effluent (aqueous solution of eriochrome black T) was executed for subsequent application of the optimized conditions in actual residual water (titration residue of complexation).

History of science to teach nature of science: A strategy for initial science teacher education

José Antonio Acevedo Díaz, Antonio García Carmona, María del Mar Aragón   
This paper presents a didactic approach for initial science teacher education on the nature of science (NDC) using the history of science (HDC). This approach is developed through a reflective reading of stories about cases and controversies from HDC, which has been made by the authors of this work. A brief description of the stories and the methodological strategy for its implementation in the classroom are included. Also, the qualitative assessment of the participants’ reflections through a rubric with levels of progression is described.


Topics of quantum chemistry: analysis of its presentation in general chemistry text books

Silvia Ramírez, Ana Fleisner, Liliana Viera   
College students show serious difficulties in learning chemistry. From research in science teaching, this problem is considered to be multicausal. We will focus on one of the possible intrinsically disciplinary causes. Among the first issues addressed in basic chemistry coursesofscientific/technologicalcareersarethosecorrespondingtoquantumchemistry. When the student approaches for the first time these subjects only knows classic contents of physics and chemistry. While many of the terms used in both contexts are the same, the ‘world’ and ‘objects’ referred to in classical physics not seem to be the same that those that is cited in chemistry. The fact that it would seem that the quantum chemistry depends on physical models available of the world, it adds the complication of using classical physics concepts in a context in which they no longer seem to have the same meaning. In this paper we analyze the way in which general chemistry textbook introduced the contents of quantum chemistry. Four aspects are considered: epistemologic choice, perspective of approach, use of the history and philosophy of science, and contextualisation of relations between quantum and classical concepts. We conclude that the modes of presentation in the texts do not contribute to a better understanding of the concepts of the discipline, nor of the mode in which the scientific knowledge is developed.


Problem-based learning as a complement to traditional teaching in Physicochemistry

Carina Lorena Fernández, María Inés Aguado   
Physicochemistry’s contents are considered as of little application in the future, and so a lot of the students direct their efforts towards a superficial learning. Problem-based learning (PBL) is a methodological strategy that seeks to stimulate the need of knowing in students and it is used as a mean to acquire knowledge and apply them to solve a real or fictitiousproblem.Thepurposeofthisarticleistodescribetheresultsofanexperienceinwhich PBL was used as a complement of traditional teaching in three student cohorts. Two instances of qualitative evaluation and three of quantitative evaluation were done. Results showed a high qualitative evaluation, emphasizing the students´ı satisfaction with the close integration of theoretical and practical contents. At the same time, the group quantitative achievements were very encouraging, even though the individual performance of the group members did not reflect the same. In conclusion, the adoption of PBL as a complement to traditional teaching is an educational investment that is fruitful at least in the short and medium term, despite the initial resistance of the students and the time and effort demanded to teachers and students.


An alternative evaluation of acid-base titrations through a simulation

Andrés Raviolo, Andrea Farré   
Thisworkshowstheresultsofalearningexperienceonacid-basetitrations,basedon the projection of a simulation, in the context of an integrating and conceptual final evaluation. This activity was done after the first year university students attended theoretical, problemsolving and lab lessons and were subjected to traditional evaluation. Students were inquired about how they had identified the different materials and entities shown in the simulation and how they had established adequate conceptual links between them. In order to evaluate the results,thesamplewasdividedintwogroupsdependingonwhethertheparticipantshadapproved or not the General Chemistry mid-term evaluation. Interesting conclusions came up about what happens when students have to draw information from a simulation to solve traditional format problems.


How can we assess if Limpics is a fake? Learning to plan investigations in secondary education

Beatriz Crujeiras, Fermín Cambeiro   
This paper presents a task designed to introduce 9th grade students (14-15 years old) to planning investigations in the Chemistry laboratory. We used a context related to everyday life:anenterprisecommitteehasjustlaunchedacampaigninschoolsinwhichtheyaskstudents tohelpthemtounmaskanotherwhohasannouncedaveryefficientdetergentcalledLimpics.To help students in planning the investigation, they were provided with coloured cards containing some questions. Their answers to these questions following a particular order will compose the planning. The analysis consists of examining students’ written designs (N=20) depending on their content and adequacy to solve the investigation. The main results point to short and little precise designs.


Aprender de las animaciones de contraste molecular con una actividad de monitorización metacognitiva

Resa M. Kelly   
Los estudiantes de Química General tienden a concebir las animaciones de fenómenos químicos como explicaciones «correctas» sin cuestionar sus limitaciones. Este estudio presenta una nueva estrategia para presentar animaciones en clases de química que demanda que los estudiantes critiquen animaciones contrastantes con el fin de determinar cuál de ellas representamejorlaevidenciacientíficapresentadaenunvideo.Elpropósitodelainvestigación fue el determinar cómo estudiantes de licenciatura en el primer semestre de un curso de Química General respondían a 2 animaciones contrastantes, una de ellas representando de manera científicamente adecuada la reacción redox entre cobre sólido y una solución de nitrato de plata y otra representando el mismo fenómeno de manera inadecuada. Se llevó a cabo un análisis de una actividad de monitorización metacognitiva para estudiar las diferencias y similitudes detectadas por los estudiantes entre las 2 animaciones, así como su propia explicación a nivel molecular del fenómeno observado. Los resultados revelan que los estudiantes fueron capaces de detectar diferencias mecánicas entre las 2 animaciones, pero tuvieron problemas para entender por qué ocurre la reacción. Independientemente de sus conocimientos de química, los estudiantes expresaron preferencia por las animaciones más simplistas y con conexiones explícitas con el nivel macroscópico.