by Elena von Hoff, Silan Toy, Thomas Waitz and Ingo Mey
Original Research
Formation of supramolecular aggregates such as micelles and vesicles is governed by hydrophobic and hydrophilic interaction as well as the geometric shapes of the aggregating molecules. Here we present an experiment for upper secondary chemistry class to show how structural properties of molecules such as fatty acids govern the shapes of aggregates. For fatty acids, the pH value controls whether micelles or vesicles are formed. Using a size exclusion column and the possibility to encase fluorescing dye molecules in vesicles, the properties of micelles and vesicles are explored and compared to typical micelle building surfactants from dish detergent and the vesicle building lecithin.
World Journal of Chemical Education. 2019, 7(2), 185-188. DOI: 10.12691/wjce-7-2-19
Pub. Date: April 10, 2019
10524 Views1965 Downloads1 Likes
by Claudia Bohrmann-Linde and Simon Kleefeld
Original Research
Thermal imaging cameras can be a very useful help when observing chemical experiments. They enable the observation of phenomena which are not visible to the human eye. In this paper a set of school experiments is described in which the use of a thermal imaging camera gives additional information on ongoing processes. Additionally an e-book that was designed as accompanying learning material is presented.
World Journal of Chemical Education. 2019, 7(2), 179-184. DOI: 10.12691/wjce-7-2-18
Pub. Date: April 09, 2019
13002 Views2219 Downloads1 Likes
by Rebecca Grandrath and Claudia Bohrmann-Linde
Original Research
Energy transition is one of the main global challenges of this century. To realize it and reach the UN´s ecological sustainability goals the topic sustainable energy and different ways of approaching energy transition have to be taught at school. As fuel cells can play a key role in the energy turnaround, they should be an integral part in chemistry education. Here we present a series of hands-on experiments focusing on alkaline, microbial and direct methanol fuel cells to help pupils understand how fuel cells work.
World Journal of Chemical Education. 2019, 7(2), 172-178. DOI: 10.12691/wjce-7-2-17
Pub. Date: April 11, 2019
19439 Views2558 Downloads1 Likes
by Amitabh Banerji, Stephan Kirchmeyer, Klaus Meerholz and Fabian Scharinger
Original Research
Organic Electronics is an interdisciplinary and cutting-edge research field leading to innovative applications and products like ultra-thin and high-efficient organic LED displays, light-weight and transparent organic solar cells or printed organic field-effect transistors (to name only few). The core functional materials in such devices are organic (semi-)conductors like conjugated polymers, oligomers or small molecules. As a sequel to our former contribution in the World Journal of Chemical Education (Vol 6, No. 1), we present in this paper a hands-on, quick and easy experiment for the synthesis of the (semi-)conductive polymer PEDOT:PSS. This experiment can be integrated into laboratory trainings and enriches the portfolio for teachers and lab-instructors dealing with organic electronics.
World Journal of Chemical Education. 2019, 7(2), 166-171. DOI: 10.12691/wjce-7-2-16
Pub. Date: April 11, 2019
10869 Views2162 Downloads
by Daniel Rauber, Frederik Philippi, Johann Seibert, Johannes Huwer, Harald Natter and Rolf Hempelmann
Original Research
Ionic liquids (ILs) are a widely investigated topic in various technical disciplines at the present time. A main focus of the research on ILs lies on applications in the field of a more sustainable, ‘greener’ chemistry that benefits from their unique property combination. This allows for the improvement of existing technologies and the use in novel, innovative processes. Especially the synergistic combination with other concepts of green chemistry is expected to lead to promising application of ILs. Regardless of their presence in current scientific research, they are covered rarely in the didactics of chemistry, although they represent an ideal subject to incorporate fundamental relationships or chemical concepts into teaching. They can also be included in various demonstration or hands-on experiments. Therefore, the topic of ILs is very promising for the transfer of knowledge from chemical research and industry into didactical experiments especially in the greater context of green chemistry. In this contribution, we present some simple experiments that utilize a multifunctional IL as recyclable catalyst in a biphasic homogenous catalysis. The experiments demonstrate the ecological and economic benefits offered by ILs in an intelligent process design compared to the conventional protocols for esterification. It is shown that exploiting the potential offered by the tunability of functional ILs as high-performance chemicals rather than ‘simple solvents’ offers many possibilities for a more sustainable chemical production.
World Journal of Chemical Education. 2019, 7(2), 153-165. DOI: 10.12691/wjce-7-2-15
Pub. Date: April 11, 2019
14531 Views2138 Downloads1 Likes
by Dominique Rosenberg, Katharina Dick, Steffen Gudenschwager, Maike Busker and Walter Jansen
Original Research
Redox-Flow-Batteries are currently being studied for the storage of wind and solar energy, especially the use of organic compounds as redox systems. With this communication we demonstrate, that these systems can be successfully used at school and in higher education. The focus is put upon the use of compounds found in bark and peat as well as humic acids.
World Journal of Chemical Education. 2019, 7(2), 145-152. DOI: 10.12691/wjce-7-2-14
Pub. Date: April 11, 2019
15528 Views1899 Downloads1 Likes
by Patrick Gräb and Ekkehard Geidel
Original Research
In chemical education, it is often a challenge to understand the basic principles of spectroscopic techniques due to missing connections to the real world. Therefore, the present contribution offers context-based applications of UV/Vis spectroscopy for analytics of food colorings with which learners can improve their skills regarding this method. The spectroscopic determination of food colorings seems to be a promising approach due to the long tradition and omnipresence of dyes in supermarket products. The therefor-required spectral data for commonly used dyes are provided for educational usage. Qualitative and quantitative analytics of food colorings in four different lemonades and chocolate beans have been used to introduce learners to important analytical techniques like sample preparation or elimination of confounding factors. These analytics also display the limitations of the method in the visible range of light in the case of tartrazine and curcumin. By applying Lambert-Beer-Bouguer’s Law in different variations, typical calculations of concentrations can be studied in quantitative analyses. The studied food samples demonstrate the different usage of food colorings depending on the country of sale. Finally, a 3D-printable low-cost photometer suitable for the discussed quantitative analytics in educational contexts is presented.
World Journal of Chemical Education. 2019, 7(2), 136-144. DOI: 10.12691/wjce-7-2-13
Pub. Date: April 11, 2019
16882 Views1972 Downloads2 Likes
by Jana Novotny, Dominik Quarthal and Marco Oetken
Original Research
The energy transition towards a larger share of renewables requires energy storage devices with redox flow batteries playing a central role for stationary large-scale storage. The most promising and developed one is the vanadium redox flow battery. However, vanadium compounds are toxic, harmful to the environment and hardly suitable for use in schools – in addition, the worldwide occurrence of vanadium minerals is limited. In Freiburg, the aim of a research project was to make the topic of storage systems accessible to students both at university and in chemistry classes, because they will be the generation that will or must help shape this development. Therefore, hybrid flow batteries with harmless electrolytes, a common metal electrode and a simplified construction needed to be built for school application. Utensils from medical technology such as plastic syringes or extension lines are well suited for building cost-effective hybrid flow batteries for chemistry lessons. With such materials, electrolytes can be circulated with a pump that generates an efficient electrolyte flow. Freiburg’s design makes it possible to charge and discharge electrolytes in just a few minutes and the electrochemical reactions get visible through colour changes. In the field of redox flow batteries where the energy is stored in two electrolytes, a high-performance cell based on iron and cerium salts is also presented. With this battery, the anolyte and catholyte can be oxidised or reduced in a short time and electrolytes which change their colours during the electrochemical reaction are used as well. Thus, the operating principle of flow batteries can impressively be demonstrated by changing the properties of the electrolytes at the phenomenological level.
World Journal of Chemical Education. 2019, 7(2), 120-135. DOI: 10.12691/wjce-7-2-12
Pub. Date: April 11, 2019
25913 Views1930 Downloads12 Likes
by Andreas Schedy, Beau Matyas and Marco Oetken
Original Research
Graphite oxide is the intermediate in the synthesis of the so-called "miracle material" of the 21st century, graphene.The synthesis of highly oxidized, yellow graphite oxide is hitherto only possible via partially toxic and explosive wet-chemical processes. Therefore, the implementation of the topic graphene in school and university lessons was not possible. Due to the existing risks and the long synthesis time, the currently prevalent synthesis methods of graphite oxide are a major problem not only for teaching but also for scientific research. The authors present a novel electrochemical synthesis process of highly oxidized, yellow graphite oxide, which completely avoids the use of corrosive or toxic substances. The synthesis time is only a few minutes and the preparation of the material can be easily carried out. Therefore, Graphene can now be easily synthesized and taught in school and university.
World Journal of Chemical Education. 2019, 7(2), 109-119. DOI: 10.12691/wjce-7-2-11
Pub. Date: April 11, 2019
13988 Views1942 Downloads2 Likes
by Catharina Schmitt, Lukas Kaiser and Michael Schween
Original Research
One of the biggest challenges for learners of organic chemistry is learning to think in competing mechanistic alternatives and using cross-linked chemical knowledge. An outstanding subject for this is the competition between SN1 and E1 reactions. In this case, it is special that the competing reactions have an identical first step and separate into different paths only from the intermediate, the second step, of the reaction. Learners who are familiar with the SN1 mechanism have the opportunity to work out the fact that in addition to the SN1 reaction, the E1 reaction is also proceeding, which more or less dominates, depending on the substrate, nucleophile or solvent and the temperature. This differentiation is undertaken with a set of experimental learning opportunities we have developed using simple qualitative analytics. Our learning opportunities are designed as contrasting cases, one of them with a variation of temperature in one setup. These allow the question why a chemical reaction can occur even though it is enthalpically unfavorable, i.e. has a positive reaction enthalpy (ΔH>0), to be answered. The latter helps the learners to realize that in addition to the enthalpy of reaction, there must be another energetic quantity that determines the thermodynamics of chemical reactions: Entropy. In the end, this leads to the discussion of the Gibbs-Helmholtz equation and, thus, to basic insights into chemical thermodynamics.
World Journal of Chemical Education. 2019, 7(2), 102-108. DOI: 10.12691/wjce-7-2-10
Pub. Date: April 11, 2019
16730 Views1868 Downloads3 Likes
by Sarah Vortmann, Dominique Remy, Jörg Klasmeier and Marco Beeken
Original Research
Two simple laboratory experiments for addressing the issue of microplastics in the aqueous environment in science teaching are developed. Extraction of microbeads from cosmetic products using a coffee pad machine makes students aware of the potential emission of microplastics into the environment by using these products. Density separation of microplastic particles from beach sediment samples on the other hand demonstrates the difficulty of dealing with the problem once the particles have entered the environment. Using the low-cost experimental set-up facilitates integration of the microplastics’ topic into laboratory teaching making science lessons vivid and more interesting.
World Journal of Chemical Education. 2019, 7(2), 96-101. DOI: 10.12691/wjce-7-2-9
Pub. Date: April 11, 2019
18373 Views1988 Downloads2 Likes
by Markus Prechtl and Roman Schmidt
Original Research
Rare Earth Elements (REEs: Sc, Y, La–Lu) are found in numerous future-oriented applications such as in magnets for green technologies and in fluorescing materials. A shortage of resources is already forecast for diverse REEs, which suggests it may be necessary to recycle these elements and optimize technologies. Both aspects will be addressed in this paper. Model experiments with regards to damage monitoring using [Eu(DBM)4TEA] and the recycling of neodymium(III) sulfate in hard disk magnets will also be presented. These are experiments for teachers and students who already have advanced experimental experience, such as trainees at vocational schools.
World Journal of Chemical Education. 2019, 7(2), 90-95. DOI: 10.12691/wjce-7-2-8
Pub. Date: April 11, 2019
15479 Views1683 Downloads14 Likes
by Laura Bögge, Marco Reinmold and Arnim Lühken
Original Research
Paper is an omnipresent and everyday composite material. However, not all papers are alike. Different kinds of paper have characteristics specific to the respective application area which are modified by the use of different paper additives in paper production. Because those paper products are an integral part of the students' everyday lives, adequate model experiments have been developed that enable the students to reproduce complex paper production processes in chemistry class. This article therefore presents two reliable hands-on experiments that show the history of paper gluing (experiment I) as well as the use and detection of polyvinyl alcohols as typical sizing agent of different kinds of paper (experiment II). Both experiments primarily use easily accessible everyday materials, which from a didactic perspective again create an everyday reference for the students. From an organizational and experimental perspective the use of everyday materials results in an inexpensive and environmentally friendly lab work with low safety-risks, so that the experiments make a valuable contribution to the introduction of paper chemistry for advanced chemistry teaching in secondary schools.
World Journal of Chemical Education. 2019, 7(2), 84-89. DOI: 10.12691/wjce-7-2-7
Pub. Date: April 11, 2019
14190 Views1334 Downloads2 Likes
by Michael Scheid, Kristina Hock and Stefan Schwarzer
Original Research
In the last few years high quality 3D printing has become quite inexpensive. Therefore, a look at its possible applications in school chemistry teaching seems worthwhile. This article deals with a project to engage upper school students in the development and production of their own molecular model set using a computer-aided design (CAD) program and a 3D printer. The presented teaching unit can be integrated into regular chemistry classes with six to eight lessons or can be offered as an elective lesson course. Part of this teaching unit is the investigation of different 3D print filaments to elaborate their chemical structure-properties-relations. The filaments are characterized by their melting behavior and by further chemical analysis.
World Journal of Chemical Education. 2019, 7(2), 72-83. DOI: 10.12691/wjce-7-2-6
Pub. Date: April 11, 2019
19967 Views1706 Downloads9 Likes
by Reza Saadat, Björn Bartram and Timm Wilke
Original Research
By adding nanoparticles to classical polymer systems, new functional materials with tailored properties can be obtained. The great variety of possibilities opens up just as many interesting fields of application for industry and science. Following on from this, this article will present how the classical educational subject area of polymers can be extended by a current research context. In a series of experiments, students are using inexpensive chemicals and simple materials from the hardware store to produce nanocomposites that have a much greater hardness or antimicrobial activity than polymers alone. Their properties can then be investigated using a simple test method. Overall, it will be illustrated, that the combination of polymer chemistry and nanotechnology offers a variety of learning opportunities and questions with curricular relevance for schools and student laboratories.
World Journal of Chemical Education. 2019, 7(2), 65-71. DOI: 10.12691/wjce-7-2-5
Pub. Date: April 11, 2019
13442 Views1867 Downloads2 Likes
by Achim Habekost
Original Research
Electrochemical simulations are presented to introduce students to the capabilities of cyclic voltammetry (CV). The systems chosen involve one and two-electron transfers, and can be delineated with CV as being reversible, quasi-reversible, or irreversible. The rate constants for the electron transfer can be estimated by the theory of Nicholson and Shain. DigiElch, professional®provides the opportunity of fitting experimental CVs after assuming a reaction scheme. We will demonstrate data fitting for two different mechanisms, electron transfer E and electron transfer followed by a chemical reaction with a subsequent electron transfer of the product ECE.
World Journal of Chemical Education. 2019, 7(2), 53-64. DOI: 10.12691/wjce-7-2-4
Pub. Date: April 11, 2019
21446 Views1747 Downloads3 Likes
by Holger Fleischer
Original Research
The reaction of Fehling’s and Benedicts’s test solutions with solutions of reducing sugars, e.g. glucose, is frequently misinterpreted with respect to the products formed. The tests are by no means suitable to detect aldehyde groups in organic molecules. The course of the reaction is known since long to be rather complex and the corresponding carboxylate, often assumed to be the major reaction product, does not occur at all. Both tests, as well as Tollens’ test using alkaline silver(I) solution, have some drawbacks for chemistry lessons, especially in students’ lab courses. The “iodine test”, well established to quantitatively determine glucose, could be a suitable alternative in many cases. It allows a quick detection, even of small amounts or reducing sugars at room temperature by decolourisation of a weakly alkaline iodine–starch–solution. The test is based on several coupled equilibria, and hypoiodous acid is the oxidizing agent. The complexity of the molecular description of the reaction can easily be reduced. Hence, the iodine test is suited to set different levels of difficulty, in lab work as well as in exams. The “iodine test” can even be used in Primary School, since the necessary solutions do not represent a danger.
World Journal of Chemical Education. 2019, 7(2), 45-52. DOI: 10.12691/wjce-7-2-3
Pub. Date: April 11, 2019
25291 Views1412 Downloads4 Likes
by Matthias Ducci
Original Research
In this article, novel experiments on the topic of redox reactions are presented. These reactions take place in small sodium alginate beads, containing some of the reactants. By immersing the beads in various solutions, the pH-dependence of the redox potentials of some redox systems and different redox states can be visualized by eye.
World Journal of Chemical Education. 2019, 7(2), 40-44. DOI: 10.12691/wjce-7-2-2
Pub. Date: April 11, 2019
12030 Views1373 Downloads1 Likes
by Rainer Brunnert, Yasemin Yurdanur and Michael W. Tausch
Original Research
An experiment simulating the natural cycle of photosynthesis and respiration – and dealing with both matter and energy conversion – is presented and theoretically elucidated. Teaching recommendations concerning the integration of the Photo-Blue-Bottle experiment into lower chemistry and biology education according to the 5E Instructional Model are provided as well as supplementary materials.
World Journal of Chemical Education. 2019, 7(2), 33-39. DOI: 10.12691/wjce-7-2-1
Pub. Date: April 11, 2019
14432 Views1738 Downloads2 Likes