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1

Remediation of CO2 in Boudouard’s reaction as an example of reversible chemical reaction

Szostak Elżbieta, Odrowąż Ewa, Górska Natalia

Chemistry-Didactics-Ecology-Metrology

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2020

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R. 25, NR 1-2

101--111

EN

One of the fundamental elements of a scientist's work is the ability to lead observations of the phenomena that surround us and based on them making conclusions. These observations are conducted within the so-called scientific experiments. Lessons learned based on the results obtained in experiments allow researchers to better understand the essence of the phenomena occurring in the world around us. Drawing conclusions is not always easy. In order to achieve this skill, we must possess a well-established knowledge in the field of the phenomenon that interests us. The most striking example of how important skills are observation and drawing proper conclusions is the phenomenon of global climate warming. The main parameter influencing temperatures registered on Earth is the concentration of greenhouse gases in the atmosphere, and especially carbon dioxide created from combustion processes. A significant role in studies of the reduction of CO2 emissions plays chemists. To be sure that conducted by them experiments are optimally designed, it is necessary to ensure them with proper education already at the secondary school level. The main aim of this article was to conduct the study in order to explain chemical issues that create the greatest cognitive difficulties among students. The second aim of the article was to propose a chemical experiment to students that would allow them to find out more about the phenomena governing in the area of problematic issues. The proposed experiment is based on the concept of solubility equilibrium. Results of preliminary tests that have been carried out after applying this experiment on a small group of students, indicated their better understanding of the studied subject.

2

Learners’ understanding of chemical equilibrium at submicroscopic, macroscopic and symbolic levels

Prokša M., Drozdíková A., Haláková Z.

Chemistry-Didactics-Ecology-Metrology

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2018

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R. 23, NR 1-2

97--111

EN

It is not easy for secondary school learners to comprehend the concept of chemical equilibrium at the level of understanding. In this context, a feedback is important for the teachers to optimize their help to students in constructing this concept. We designed and tested sets of particularly prepared tasks, the solution of which reflects the depth of understanding of the basic concept in macroscopic, submicroscopic and symbolic representation. Difficulties in understanding the chemical phenomena and concepts do not result only from the existence of these three levels or from their explanation using abstract concepts, but also from the lack of interconnection between these representations. Consistent interconnection of these levels can lead to an internal conflict in students, and consequently to a more profound understanding of the concept or relationships between concepts at multiple levels of representation to understand them or to change the meaning of one to another. There is also a close connection with the aspect of memory, algorithmic and conceptual approaches to solving educational situations, which extends dimensionally and reinforces the need for a more comprehensive grasp of learners’ mastery of the given concept. The teacher cannot expect that the learners without intensive training, e.g., only by observing the macroscopic representation, can interpret the essence of the submicroscopic representation. Therefore, these aspects need to be consistently involved in the model of learners’ cognitive process early enough to apply them in the educational practice without any problems.

PL

Uczniom szkół średnich nie jest łatwo zrozumieć pojęcie równowagi chemicznej. W tym kontekście ważna jest informacja zwrotna dla nauczycieli, aby zoptymalizować ich pomoc dla uczniów w konstruowaniu tej koncepcji. Zaprojektowano i przetestowano zestawy specjalnie przygotowanych zadań, których rozwiązanie odzwierciedla głębokość rozumienia podstawowej koncepcji w reprezentacji makroskopowej, submikroskopowej i symbolicznej. Trudności w zrozumieniu zjawisk chemicznych i pojęć nie wynikają jedynie z istnienia tych trzech poziomów lub z ich wyjaśnienia za pomocą abstrakcyjnych pojęć, ale także z braku wzajemnego połączenia między tymi reprezentacjami. Odpowiednie wzajemne połączenie tych poziomów może prowadzić do wewnętrznego konfliktu w umysłach uczniów, a w konsekwencji do głębszego zrozumienia koncepcji lub relacji między pojęciami na wielu poziomach reprezentacji, aby je zrozumieć lub zmienić ich znaczenia. Istnieje również ścisły związek z aspektem pamięci, algorytmicznym i koncepcyjnym podejściem do rozwiązywania sytuacji edukacyjnych, który rozszerza się wymiarowo i wzmacnia potrzebę bardziej wszechstronnego opanowania przez ucznia danej koncepcji. Nauczyciel nie może oczekiwać, że uczący się bez intensywnego treningu, np. tylko obserwując makroskopową reprezentację, mogą interpretować istotę submikroskopowej reprezentacji. Dlatego te aspekty muszą być konsekwentnie włączane w model procesu poznawczego ucznia wystarczająco wcześnie, aby zastosować je w praktyce edukacyjnej bez żadnych problemów.

3

Bilevel limit analysis of self-hardening rod systemsunder moving load

Alawdin P., Urbańska K.

Computer Assisted Methods in Engineering and Science

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2017

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Vol. 24, no. 4

225--238

EN

This paper considers results of an analysis of self-hardening systems (SHS), i.e. load-carrying systemswith improved strength and rigidity. The indicated structural features can be only found if geometricalnonlinearity is taken into consideration. Material deforming diagrams can be non-monotonic and non-smooth, and constraints can be unilateral, with gaps. Furthermore, optimisation of a mathematical modelof a rod structure as a discrete mechanical system withstanding dead (constant) and/or moving loadsis proposed. This model is formulated using bilevel mathematical programming. The limit parametersof standard loads and actions are found in the low-level optimisation. An extreme energy principle isproposed to obtain the limit parameters of these actions. Onthe upper level, the parameters of movingload are maximized. A positive influence of equilibrium or quasi-equilibrium constant load with the possiblepreloading of SHS is shown. A set of criteria for the stability of plastic yielding of structures, including non-smooth and non-convex problems of optimisation is given. The paper presents an exemplary application of the proposed method which takes into account the self-hardening effect.

4

A determination of equilibrium constants for syntheses of methyl-tert-butyl and ethyl-tert-butyl ethers on sulfonic copolymer by gas chromatography

Słomkiewicz P.M.

Polish Journal of Chemical Technology

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2006

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Vol. 8, nr 2

97-101

EN

A method of determining equilibrium constants of catalytic reactions was described using gas chromatography. Both the equilibrium constants and enthalpies of methyl-tert-butyl ether from methanol and isobutene, ethyl-tert-butyl ether from ethanol and isobutene on catalyst Amberlyst 15 in the gas phase were determined. The enthalpy values of these reactions were compared with the enthalpies calculated from thermodynamic data and the experimental data given in the literature.

5

Evaluation of equilibrium constans - a new approach

Janecki D., Michałowski T.

Chemia Analityczna

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1999

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Vol. 44, No. 3B

611-621

EN

A criterion of adequacy of physicochemical data: stability constants (Kijk) of complexes, dissociation constants, activity coefficient (f) of hydrogen ion is presented. The data obtained from repeated titrations made in titrand + titrant systems of high ionic strength provide linear relationships between logKijk and f, and relative error (% e) of determination of weak acid (HnL) concentration. The relationships enable to evaluate the logKijk and f values corresponding to % e = O, preferably according to the interpolation procedure. The accuracy depends on the degree of linearity between the variables considered. This idea was employed in the determination of Kijk for complexes NaiKjHkL formed by anions of tartaric acid and was found to be promising.

PL

Zaprezentowano nowe kryterium poprawności otrzymywanych danych fizykochemicznych takich jak: stałe trwałości kompleksów Kijk, stałe dysocjacji i współczynnik aktywności! Nowa metoda wykorzystuje fakt liniowej zależności między logKijk ii, a % e. Metodę, przetestowano na przykładzie kompleks u NaiKjHkL.