by A. Habekost
Original Research
Processes at electrodes can be monitored simultaneously electrochemically and spectroscopically. In electrochemical science, expensive equipment is needed to study these spectroelectrochemical processes. Because of the high price of these instruments, they are often not used in university education. Several experiments of three chemiluminescence systems with low-cost instruments are presented and partly compared with the expensive setups
World Journal of Chemical Education. 2023, 11(4), 149-156. DOI: 10.12691/wjce-11-4-4
Pub. Date: December 18, 2023
by Surusch Djalali, Amitabh Banerji, Martin Kleinschmidt, Peter Gilch and Lena Halbrügge
Original Research
Atoms and molecules with two unpaired electrons can adopt singlet and triplet spin multiplicities. The implications of this are far reaching. For instance, the properties of molecular oxygen with its triplet ground state cannot be understood if this is not considered. In the design of emitters for OLEDs, the energy gap between singlet and triplet excitations is of utmost importance. This energy gap equals twice the exchange energy. Because of this relevance, the exchange energy is treated in textbooks and courses on physical and quantum chemistry. The treatments are commonly based on the quantum mechanical formalism and leave the students wondering why the exchange energy is non-zero. Here, the formalism is briefly re-iterated. Then wavefunctions for singlet and triplet states with identical configurations are visualized relying on the well-known particle-in-a-box model. The visualization shows that in the triplet state the electrons “automatically” avoid each other. This lowers the triplet energy compared to the singlet one. Some short comings of this didactic approach are also discussed.
World Journal of Chemical Education. 2023, 11(4), 141-148. DOI: 10.12691/wjce-11-4-3
Pub. Date: December 10, 2023
by Arijit Das, Digvijoya Sarmaa, Paresh Debnath and Bijaya Paul
Original Research
Chromatography is an essential physical technique that allows the constituent components of a mixture to be identified, separated, and purified in preparation for qualitative examination. Paper chromatography (PC) is a sort of planar chromatography, which refers to a stationary phase that is a solid, flat surface. In this illustration stationary phase is a particular kind of paper (Whatman quantitative filter paper grade 41). The fundamental idea behind paper chromatography is the differential passage of a mixture's constituent parts through filter paper or chromatography paper. A quick method for separating mixtures of metal ions, amino acids, carbohydrates, colors, and pharmaceuticals is paper chromatography (PC). For this qualitative analysis, only a very small sample is needed. Metal cation separation has seen increased by the use of the PC approach. Here, the four experiments show how PC may be used to separate metal ions [(Pb2+ & Cu2+), (Ni2+ & Co2+), (Cu2+ & Fe3+), (Cu2+ & Co2+)] based on their colored spots and the retardation factors or retention factors (Rf) values by using different eluting solutions.
World Journal of Chemical Education. 2023, 11(4), 134-140. DOI: 10.12691/wjce-11-4-2
Pub. Date: November 07, 2023
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by Naoki Maruyama and Toratane Munegumi
Original Research
Cicada shells are widely available and have been used to teach insect anatomy; their tactile nature is ideal for students who are reluctant to handle living insects. The main component of cicada shells is chitin, which has a polymer structure of N-acetylglucosamine that produces an amorphous gel in neutral aqueous solutions. Glucosamine has a reducing group (hemiacetal structure) and an amino group, and these functional groups can be detected with Benedict reagent and ninhydrin, respectively. This research proposes a procedure to detect the glucosamine structural features present in cicada shells and highlights the link between chemicals in the cicada shells and the environment. Cicada shells can thus be useful for teaching classes about chemicals and their role in the environment.
World Journal of Chemical Education. 2023, 11(4), 127-133. DOI: 10.12691/wjce-11-4-1
Pub. Date: October 17, 2023
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