by Malte Petersen, Paul Worliczek, Johannes B. Max, Afshin Nabiyan, Manuel Wejner, Jonas Eichhorn, Carsten Streb, Felix H. Schacher and Timm Wilke
Original Research
In current research, molecular light-driven catalytic units are linked to hierarchically structured soft matter matrices and used to convert solar radiation into chemical reactivity for photocatalytic water splitting. This article describes the development of a simplified hydrogen evolution reaction that transfers selected results to the student laboratory in a phenomenon-oriented manner. For this purpose, a photocatalytically active system - consisting of the catalyst titanium dioxide, the dye Eosin Y and the electron donor triethanolamine - is combined with two polymers as suitable matrices. A newly developed, low-cost hydrogen detector is used to quantify the hydrogen concentration.
World Journal of Chemical Education. 2021, 9(4), 190-196. DOI: 10.12691/wjce-9-4-12
Pub. Date: November 28, 2021
3197 Views20 Downloads
by Philipp Lanfermann, Christoph Weidmann, Janina Dege, Steven Celik, Alexander Tasch, Mona Christin Maaß and Thomas Waitz
Original Research
This paper presents two related experiments aimed at determining the efficiency of photocatalytic hydrogen production on ZnS/CdS nanoparticles. In the first experiment, the method of chemical actinometry is applied to measure the number of light quanta emitted by the UV LEDs used. This utilizes the formation of an iron(II)-1,10-phenanthroline complex (ferroin), the concentration of which can be determined photometrically. In the second experiment, hydrogen is produced on prepared ZnS/CdS with the aid of these LEDs, the yield is determined by collecting the generated volume of hydrogen gas and the efficiency is calculated.
World Journal of Chemical Education. 2021, 9(4), 185-189. DOI: 10.12691/wjce-9-4-11
Pub. Date: November 28, 2021
2885 Views9 Downloads
by Marc Zimmermann, Dennis Domke and Michael Schween
Original Research
This article first describes photochemical bromination reactions of two different reactants proceeding via electron septet intermediates according to the radical substitution reaction mechanism (SR). The case comparison is intended to enable learners – high school or university first-year organic chemistry students – to work out the concept of hyperconjugation, which is very significant for organic chemistry, by intertwining experimental results and theoretical interpretation (of free radical intermediates) closely. Since students often do not succeed in transferring concepts they have already learned from one mechanism to another, the second step will be to transfer and apply the concept of hyperconjugation to carbenium ions as reactive intermediates by means of an analogous experimental case comparison of first-order nucleophilic substitution reactions (SN1).
World Journal of Chemical Education. 2021, 9(4), 175-184. DOI: 10.12691/wjce-9-4-10
Pub. Date: November 28, 2021
4205 Views9 Downloads
by Heiko Hoffmann and Michael W. Tausch
Original Research
Photochemistry is an important topic which is relevant regarding the usage of solar light as clean energy source. By employing photoreactions, a broad variety of molecular transformations can be conducted which is different from classical thermal chemistry. Ketones provide advantages and thus can be used as model compounds to develop central aspects and principles of photochemistry for teaching purposes. A photochemical experiment for university teaching, dealing with the basic reaction modes of ketones with γ-C-H-bonds, can be introduced and adjusted to the learners capability and pre-knowledge. Different basic characteristics of photochemistry and radical reactions as well as advanced topics and working techniques can be accessed in a hands-on-way using the model reaction. Depending on the equipment and the time frame available, the experiment can be conducted on preparative or on micro scale.
World Journal of Chemical Education. 2021, 9(4), 163-174. DOI: 10.12691/wjce-9-4-9
Pub. Date: November 28, 2021
3638 Views19 Downloads
by F. Wetzel, T. Braun, T. Schindler and A. Habekost
Original Research
N-(Phosphonomethyl)glycine (glyphosate), known by the trade name Roundup®, is a broad-spectrum systemic herbicide used to kill various types of weeds. It was first synthesized in 1970 by John E. Franz, a chemist at the Monsanto agrochemical company. Glyphosate's mode of action is to inhibit a plant enzyme involved in the synthesis of some aromatic amino acids (“shikimate way”). The use of Roundup® is currently controversial, as its hazard potential has not been clarified. Glufosinate (2-Amino-4-[hydroxy(methylphosphonoyl)] butanoic acid) was discovered by German and Japanese scientists in a biological process: Species of Streptomyces bacteria produce a tripeptide that consists of two alanine residues and an amino acid that is an analogue of glutamate named phosphinothricin. Phosphinothricin was first synthesized by scientists at Hoechst (now Aventis) in the 1970s as a racemic mixture; this racemic mixture is called glufosinate. This article presents reliable and easily performed spectroscopic and (spectro)electrochemical measurements for identifying glyphosate and glufosinate.
World Journal of Chemical Education. 2021, 9(4), 152-162. DOI: 10.12691/wjce-9-4-8
Pub. Date: November 28, 2021
4833 Views19 Downloads
by Patrick Gräb, Ekkehard Geidel and Hans-Christian Schmitt
Original Research
Teaching the basic principles of molecular spectroscopic techniques on an experimental basis is often a particular challenge due to the relatively high cost of the required experimental equipment. The present contribution therefore offers an experimentally-based introduction into the field of spectroscopy using low-cost devices for practical courses at undergraduate level and for chemistry lessons in high schools. Using low-cost devices are also useful for schools in developing countries or poorly-funded school systems. Several experiments, specifically tailored for chemistry lessons, are developed, aiming to provide a close relation to the everyday life experience of students. Initially, a simple spectrometer working within the visible range of light is constructed by the student themselves. This low-cost dispersive spectrometer is employed for quantitative food analyses. In a second step, an introduction to spectroscopy in the near-infrared range is given using an example based on the identification of plastics. On this basis, a model experiment using a self-constructed apparatus for plastic waste separation in miniature was developed. Finally, experiments in the mid-infrared range are presented. They introduce into the functionality of a Michelson interferometer and demonstrate the use of low-cost carbon dioxide sensors. Using this strategy, students gain easier access to an understanding of radiation-matter interaction.
World Journal of Chemical Education. 2021, 9(4), 144-151. DOI: 10.12691/wjce-9-4-7
Pub. Date: November 28, 2021
3696 Views14 Downloads
by Matthias Ducci
Original Research
Diazotype is a historical light tracing process which was used, in particular, for reproducing technical drawings. This paper first explains the principle of the diazotype. Thereafter, a researching and developing teaching concept with a varity of newly developed experiments is presented for chemistry lessons at secondary level II.
World Journal of Chemical Education. 2021, 9(4), 136-143. DOI: 10.12691/wjce-9-4-6
Pub. Date: November 28, 2021
5132 Views13 Downloads
by Julian Venzlaff and Claudia Bohrmann-Linde
Original Research
The future hunger for hydrogen in industry or for private cars will demand a growing production rate and will have to meet the requirements of sustainability. Photoreforming biomass to produce green hydrogen seems to be a promising way for fulfilling sustainable industrial processes. In this article the photoreforming of sugars is used as an example to implement this subject in science classes. For educational purposes an experiment is presented that demonstrates the photoreforming of a glucose solution with a TiO2/Pt-photocatalyst. The developed gas can be examined by gas chromatography or a detonating gas test. The aim of implementing this subject in school is to pick out an innovative way of producing (green) hydrogen. Photoreforming of biomass is also a suitable context to discuss and evaluate social, environmental and economical perspectives for sustainable energy resources and industrial processes in the chemistry classroom. Students can discuss different ways of how to reach the sustainable development goals presented by the United Nations in 2015 and learn to deal with contradictions by reaching these goals. This subject is therefore ideal for integrating education for sustainable development (ESD) in school education.
World Journal of Chemical Education. 2021, 9(4), 130-135. DOI: 10.12691/wjce-9-4-5
Pub. Date: November 28, 2021
2865 Views16 Downloads
by Rebecca Grandrath, Matthias Teeuwen and Claudia Bohrmann-Linde
Original Research
Various questionnaire-based studies were carried out to get an impression of the (pre-)concepts and understanding of the scientific term “energy” in different age groups. In addition to primary school pupils, secondary school pupils and pre-service teachers, the impressions of in-service teachers were also obtained using similar questionnaires. In this article, the results of the studies are brought together in order to identify a need for action at school teaching the scientific energy concept.
World Journal of Chemical Education. 2021, 9(4), 121-129. DOI: 10.12691/wjce-9-4-4
Pub. Date: November 28, 2021
2677 Views17 Downloads
by Richard Kremer and Michael W. Tausch
Original Research
Photocatalytic hydrogen production without the bypass via photovoltaics and electrolysis has been realized using a versatile photocatalytic system with only three components: the redox mediator ethyl viologen, the photocatalyst proflavin and the sacrificial donor EDTA. By adding a reduction catalyst made of nano-platinum on alumina to the aqueous solution of these three chemicals, hydrogen can be produced by irradiation with sunlight.
World Journal of Chemical Education. 2021, 9(4), 111-120. DOI: 10.12691/wjce-9-4-3
Pub. Date: November 28, 2021
4227 Views19 Downloads
by Lena Halbrügge, Amitabh Banerji and Sven Rösler
Original Research
Printed electronics is an emerging research field and is going to play a vital role in our everyday-life in the near future. Luminescent printed electronic devices can be very thin and flexible, which makes them feasible for new applications. Such EL-devices are already being applied in automobiles. For the school-implementation of printed electronics the authors have developed a flexible EL-device, which can be hand-printed using low-cost materials and methods.
World Journal of Chemical Education. 2021, 9(4), 104-110. DOI: 10.12691/wjce-9-4-2
Pub. Date: November 28, 2021
2952 Views12 Downloads
by Nico Meuter, Sebastian Spinnen and Michael W. Tausch
Original Research
This mini review presents a series of experiments in which light acts on two general phenomena: isomerization reactions and photoluminescence. The experiments described using the reversible photoactive molecular switch spiropyrane/merocyanine, is suited to teach fundamental concepts of photochemistry as well as to introduce innovative applications related to smart materials, molecular motors and logic gates.
World Journal of Chemical Education. 2021, 9(4), 96-103. DOI: 10.12691/wjce-9-4-1
Pub. Date: November 28, 2021
3921 Views11 Downloads