Band 5, Heft 1 - Chemistry and Cultural heritage

This article describes two of the most common natural sources of red anthraquinones that have been used since antiquity for textile dyeing and as lake pigments, namely cochineal insect and the roots of Rubia and Relbunium plants. Carminic acid is the main component of carmine, the red colorant obtained from cochineal. Alizarin and purpurin are found in the extracts of Rubia roots, but Relbunium roots contain only purpurin. These red anthraquinones have been identified in a variety of cultural heritage objects. High performance liquid chromatography with diode array detection (HPLC-DAD) is described as the most suitable analytical technique for the identification of these dyestuffs, particularly in micro-samples from textiles or pigment layers in paintings and polychrome sculptures. Finally, application of HPLC-DAD analysis to the identification of lake pigments in micro-samples of mural paintings of two eighteenth century Andean churches in Peru is described.

The purpose of the study was to assess strategies for enhancing the integration of cultural practices into the teaching and learning of chemistry in secondary schools. The study adopted a descriptive survey research design and the population of the study comprised 19,920 respondents. Two research questions and two hypotheses guided the study. The instrument used for data collection was “Strategies Enhancing Integrating Cultural Practices Questionnaire (SEICPQ)” developed by the researchers. Mean and standard deviation were used to answer the research questions and t -test statistic was used to test the null hypotheses at 0.05 significance. The result revealed that incorporation of cultural practices into the chemistry curriculum content and adequate training of teachers on the integration of cultural practices in teaching chemistry and among others were identified as strategies that could enhance the integration of cultural practices. Non-incorporation of cultural practices into the chemistry curriculum content among others were identified as factors affecting the integration of cultural practices. The results also revealed that teachers and students do not significantly differ on their responses on strategies enhancing as well as the factors militating against the integration of cultural knowledge and practices into teaching of chemistry. Necessary conclusions were made.

The chemistry and cultural heritage can be integrated in an interdisciplinary way into teaching the Chemistry, from primary to secondary school and university, including learning about the specifics of works of art in the context of their preservation or care. The main purpose of this study is to determine the pre-service Chemistry, Primary school, and Fine art teachers’ views about promoting an interest in the cultural heritage and Chemistry learning through materials of work of art from the chemistry perspective. The study revealed that pre-service teachers do not have sufficient knowledge and experience regarding cultural heritage from the point of view of chemistry (materials and techniques of fine art), and all groups show an interest in the mentioned contents. This integrated and interdisciplinary approach to teach Chemistry and cultural heritage is presented to the pre-service teachers as part of the general elective course that was developed on the basis of this preliminary research about pre-service teachers’ views regarding these topics.

Collectively, we have chosen to explore an Australian First Nations-first approach to understanding the chemical elements. We believe that engagement with cultural heritage, ongoing cultures, and the knowledges of this place —the lands on which we work, live, and study—will lead to new ways of understanding the elements and change the way we practice chemistry. The “First Nations first” phrase and approach comes from understanding the unique place that Aboriginal and Torres Strait Islander peoples have in the Australian context. In this paper we explore how a First Nations-first approach could take place in Sydney on Aboriginal lands. This approach is led by Aboriginal people, engages with culture, and is produced with local knowledge holders. So far, the work has entailed two years of meeting, conversing, and sharing space to determine appropriate ways of working together, interrogating the complexities of the ideas, and to refining our approach to the work. To appreciate the significant shift that a First Nations-first approach represents for chemistry, we consider the legacy of the Periodic Table. We share some reflections on how Indigenous knowledges can contribute to an expanded chemistry curriculum through the recognition of productive cultural tension.

Introduction to Conservation Science (ICS) is a curricular unit (CU) from the bachelor’s degree in Conservation-Restoration at NOVA School of Science and Technology. This CU was created in 2017 to fill a gap in the academic degree – the need for a bridge between fundamental sciences (1st year) and conservation-restoration diagnosis (3rd year). For this reason, ICS was designed with the main goal of teaching 2nd year students how to look at, approach and solve problems of Cultural Heritage, through the combination of reflexive thinking and object-led analysis. ICS was first designed by an expert in Conservation Science with academic background in physics. However, from the perception of the students’ struggle to understand the purpose of ICS subjects to their future professional activity, a professor with expertise in Conservation and Restoration was invited in 2019 to work together in the re-design of the CU, through an integrated approach between the two experts. ICS was then revised with the introduction of new perspectives and topics, as well as new communication routes to students. This work highlights this partnership as a good practice methodology to involve conservation-restoration students into science, focusing on the ICS classes specifically dedicated to radiation, colour, and museum lighting.

The oxidation number and number of transferred electrons are two paramount parameters in the study of redox reactions. Their calculations are both important and challenging. The oxidation number of organic carbons is used in organic chemistry, biochemistry, and applied chemistry. Combustion reaction is a classical type of redox reaction, in which the oxygen molecule (O 2 ) is the oxidizing agent. In this article, the integration of three sets of relations is explored by using the method of balancing organic combustion: (i) number of transferred electrons and oxidation number of organic carbons, (ii) mole of oxygen molecule and number of transferred electrons, and (iii) oxidative ratio, oxidation number of organic carbons, and number of transferred electrons. This method can also establish the relationships among the stoichiometric coefficients, mole of oxygen molecule, oxidative ratio, number of transferred electrons, and oxidation number of organic carbons. Furthermore, the oxidation number of organic carbons and the number of transferred electrons of a given organic compound can be determined by the derived mathematical equations.

In this paper we describe an intervention study on the application of the octet rule. This study was conducted at a German University with students in their first- and second undergraduate year. As repeatedly observed by us before, the evaluation of the study confirmed that the students have difficulties with the application of the octet rule in general, but above all for charged molecules. After an intervention, which consisted of a detailed checklist for the application of the octet rule and training opportunities, the students’ competences increased, especially for the tasks which included charged molecules. Students’ explanations were not as good as expected; the linguistic quality did not increase significantly from pre-to post-test. This is not surprising, because the training of argumentation skills was not part of the intervention. The intended goal, training the application of the octet rule, has been achieved.

Limiting reactants is a crucial factor in any reaction. Students found it a tricky topic. The current study has intended to conduct a kitchenette experiment, in which a student will follow the instructional procedure to determine a limiting reactant in a self-learning process. The study has adopted an experimental approach. A program was developed in C++ as an efficient tool to determine the limiting reactant. The major outcomes drawn from the study have enlightened the significance of a balanced equation in obtaining the correct molar ratio. It has also been noted that molar ratio similarity in a particular balanced equation can wrongly lead to an erroneous assumption.

Commercially available molecular models are elaborately made but generally expensive, which hinders their distribution to all classroom students. Aiming at developing an affordable molecular model, we developed a structure model kit consisting of inexpensive electronic components including transistors and colored light-emitting diodes (LEDs) with a total cost of ca . 2 USD. The structure model kit was designed for building a family of environmental pollutant molecules known as dioxins, in which transistor, white LED, red LED, and yellow LED components are used to represent sp 2 carbon, hydrogen, oxygen, and chlorine atoms, respectively. Herein, we report an activity directed to nonchemistry majors studying environmental science and electronic engineering to help them gain insight into the molecular structure of dioxins using the newly developed structure model kit. The activity was well received by many students, some of whom came to understand the relationship between the structure and nomenclature of dioxins, mainly 2,3,7,8-tetrachlorinated dibenzo- p -dioxin (2,3,7,8-TCDD) and its isomers.

Man-made activities can release the ozone depleting substances (ODSs) like chlorofluorocarbons (CFCs) and other halocarbons stable in atmosphere and ultimately, they migrate to the stratosphere where they can destroy the ozone layer through the XO x catalytic cycle (X = Cl, Br). The active forms in this catalytic cycle are X and XO that can be arrested in the inactive forms like XONO 2 (halogen nitrate, an additive compound of two odd electron molecules XO and NO 2 ) and HX (produced in the reaction of X with CH 4 ) in the stratosphere to prevent the ozone depletion cycle. The catalytically active forms from these inactive species can be regenerated in the reactions on heterogeneous solid surface like polar stratospheric cloud (specially Type II PSC formed at about −85 °C). Formation of such PSC in the stratosphere is only possible in the supercooled stable Antarctic vortex produced in the prolonged winter. In fact, formation of such PSC in the stratosphere is not possible in the other regions of the earth and not even in the Arctic pole where no stable Arctic vortex is generally formed in the winter. Thus nature confines the ozone depletion reactions mainly in the stratosphere of Antarctica pole which is practically inhabited.