Wszystkie pola: chemical thermodynamics - Katalog OPAC zbiorów

Skocz do pozycji: 1.

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

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Skocz do pozycji: 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

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Skocz do pozycji: 3.

Tytuł:: Investigations on Chemical, Thermal Decomposition Behavior, Kinetics, Reaction Mechanism and Thermodynamic Properties of Aged TATB
Autorzy:: Singh, A.
Kaur, G.
Sarkar, C.
Mukherjee, N.
Powiązania:: https://bibliotekanauki.pl/articles/357970.pdf
Data publikacji:: 2018
Wydawca:: Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:: 1,3,5-triamino-2,4,6-trinitrobenzene
thermal decomposition
kinetics
thermodynamics
Opis:: 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) is a kind of insensitive high explosive that can be used as an energetic material in nuclear weapon and space applications. In this work, we have studied the effect of aging on the properties of TATB from a 20 year old lot that had been in direct contact with casing and natural environment conditions. The kinetics was studied using the temperature at the maximum reaction rate (peak) and isoconversional methods from TGA and DTA data obtained at five heating rates under a nitrogen atmosphere. The properties investigated for thermal stability indicate that there is no change in the properties during prolonged exposure in natural environment conditions. The activation energy calculated by the Kissinger method was 179.9 kJ·mol−1 by DTG and the 176.9 kJ·mol−1 by DTA. The experimental results of kinetic analysis obtained by isoconversional methods are in good agreement and very close to each other. In the analysis of reaction mechanisms, the reaction models could be probably best described by a surface contraction mechanism using the Coats-Redfern and Criado methods. The thermodynamic parameters such as Gibbs free energy, enthalpy and entropy of activation were also investigated. The self-accelerating decomposition temperature (TSADT) and critical temperature for thermal explosion (Tb) were also calculated.
Źródło:: Central European Journal of Energetic Materials; 2018, 15, 2; 258-282
1733-7178
Pojawia się w:: Central European Journal of Energetic Materials
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Badanie wpływu wodorku glinu na skład chemiczny produktów i ciepło spalania złożonych paliw rakietowych
Investigation of the Influence of Aluminium Hydride AlH3 on the Chemical Composition and Heat of Combustion of Composite Propellants
Autorzy:: Papliński, A.
Zygmunt, B.
Powiązania:: https://bibliotekanauki.pl/articles/403835.pdf
Data publikacji:: 2014
Wydawca:: Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
Tematy:: termodynamika
złożone paliwa rakietowe
wodorek glinu
produkty spalania
thermodynamics
composite propellant
aluminium hydride
combustion parameters
Opis:: W pracy przedstawione zostały wyniki analizy składu chemicznego oraz parametrów termodynamicznych produktów spalania złożonych paliw rakietowych zawierających wodorek glinu AlH₃. Rozpatrywane są paliwa oparte na chloranie(VII) amonu (NH₄ClO₄), w których jako lepiszcze stosowany jest kauczuk typu HTPB. Jako składniki energetyczne paliwa rozpatrywane są Al i AlH₃. Przedmiotem pracy jest zbadanie, w jaki sposób zastąpienie Al przez AlH₃ wpływa na skład chemiczny i właściwości produktów spalania. Skład chemiczny i parametry termodynamiczne produktów spalania określono za pomocą programu obliczeniowego MWEQ. Przy zachowaniu tego samego udziału masowego, wprowadzenie AlH₃ zamiast Al prowadzi do obniżenia temperatury produktów przemiany, wzrasta ilość moli produktów w stanie gazowym, odniesiona do jednostki masy paliwa. Uzyskane wyniki potwierdzają przydatność wodorku glinu AlH₃ jako perspektywicznego składnika energetycznego paliw rakietowych.
The influence upon chemical composition and heat of combustion of composite propellant that occurs as a result of substitution of aluminium by its hydride AlH₃ is investigated. Propellants based on ammonium chlorate(VII) (NH₄ClO₄) modified by standard HTPB binder are considered. Chemical composition and thermodynamic parameters of combustion products are evaluated by MWEQ computer program supplied with large species database. The particular attention is paid to proper choose of thermodynamic data describing temperature dependence of heat capacity, enthalpy and entropy of chemical compounds belonging to Al-Cl-O-H group. The alteration of chemical composition and temperature of combustion products that is followed by replacement of Al by AlH₃ is illustrated in a quantitative mode. The prospective applicability of AlH₃ as an energetic component of composites propellants is confirmed.
Źródło:: Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa; 2014, 5, 1 (15); 41-50
2081-5891
Pojawia się w:: Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa
Dostawca treści:: Biblioteka Nauki

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