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Wyszukujesz frazę "chemical thermodynamics" wg kryterium: Temat


Wyświetlanie 1-2 z 2
Tytuł:
O siłach napędowych w przyrodzie : koncepcje, interpretacje, nieporozumienia
About driving forces in nature : concepts, interpretations and misunderstandings
Autorzy:
Orlik, Marek
Powiązania:
https://bibliotekanauki.pl/articles/2200428.pdf
Data publikacji:
2023
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
termodynamika chemiczna
entropia
entalpia swobodna
energia swobodna Helmholtza
współrzędna reakcji
reguła Le Chateliera-Brauna
chemical thermodynamics
entropy
free Gibbs energy
free Helmholtz energy
reaction coordinate
Le Chatelier-Braun principle
Opis:
Prepared for presentation within the Didactic Section of Polish Chemical Society, the study summarizes selected problems and concepts of teaching the basics of chemical reaction energetics as part of chemical undergraduate studies. The following problems are discussed: 1) indication of misunderstandings related to the definition of standard states in thermodynamics, with particular emphasis on the unfortunate assignment of the temperature of 298.15 K as "standard temperature", 2) problems with the interpretation of entropy as a "measure of disorder", with a recommendation regarding for understanding entropy as a measure of the number of ways to distribute the total energy of the system between the available degrees of freedom of motions, in terms of the quantum representation, i.e. the energy characteristics of a substance through sequences of energy levels, 3) a proposal to introduce the issue of thermodynamic driving forces of a chemical reaction based on the characteristics of the water evaporation process under different conditions, which favors the distinction of any reaction driving force from its standard driving force, as well as the distinction of such forces for isochoric and isobaric systems, both one- and multi-component, (4) the necessity to take into account the entropy of mixing of reagents to deepen the understanding of changes in the driving force of the reaction on the way to the state of chemical equilibrium, and 5) various interpretations of the influence of temperature on the equilibrium composition of the reacting system (Le Chatelier-Braun rule), with a recommendation for molecular interpretation, showing the role of differences in energies and sequences of energy levels of reactants and products for the value and direction of changes of the equilibrium constants of the reaction with temperature, taking into account also the principles of statistical thermodynamics. An additional aim of the article is to emphasize the importance of elementary mathematical education for mastering the basic laws governing the course of physicochemical processes, as well as for true understanding of chemistry, in general.
Źródło:
Wiadomości Chemiczne; 2023, 77, 1-2; 1--34
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermodynamic analysis on disproportionation process of cyclohexylamine to dicyclohexylamine
Autorzy:
Valeš, Roman
Dvořák, Bohumír
Krupka, Jiří
Powiązania:
https://bibliotekanauki.pl/articles/1849317.pdf
Data publikacji:
2021
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
Cyclohexylamine
Dicyclohexylamine
Disproportionation
Chemical equilibrium
Thermodynamics
Opis:
This work deals with a study of the effect of temperature on the cyclohexylamine disproportionation to dicyclohexy-lamine, conjointly with the thermodynamic analysis of this process. The laboratory experiments were carried out in a glass tubular continuous-flow reactor in a gaseous phase at the reaction temperature 433–463 K over a nickel catalyst. The results show, that the temperature has a trifing effect on equilibrium conversion of cyclohexylamine. However, temperature affects the formation of hydrocarbons, benzene and cyclohexane, and dehydrogenation products of dicyclohexylamine, i.e. N-cyclohexylidenecyclohexanamine and N-phenylcyclohexylamine. The latter one is the dominant product of dicyclohexylamine dehydrogenation. The disproportionation of cyclohexylamine has slightly exothermic character. At the experimental reaction temperature range, the cyclohexylamine disproportionation is spontaneous reaction and other reactions of this process are non-spontaneous.
Źródło:
Polish Journal of Chemical Technology; 2021, 23, 3; 43-48
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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