Sample records for CINETICA DE LAS REACCIONES QUIMICAS (chemical reaction kinetics)
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1

Introducción a la cinética química: efecto de un extracto vegetal sobre el mecanismo de oxidación del fe (ii)/ Introduction to the chemicals kinetics: effect of a vegetabl extract on the oxidation mechanism of fe(ii)

Navas, Petra Beatriz; Carrasquero-Durán, Armando
2008-12-01

Resumen en español Se propone el estudio de la cinética de la oxidación del complejo hierro (II) ofenantrolina como una experiencia didáctica para un curso de Cinética Química a nivel universitario, en la cual se incluyen tres momentos didácticos: Primero, una revisión de los conceptos químicos relacionados con el comportamiento de las sustancias involucradas en la reacción, seguido del diseño de mapas de conceptos y de los experimentos. Posteriormente se obtienen los resultados e (mas) xperimentales que se emplean en la validación de los mecanismos de reacción propuestos. La transformación del ion ferroso en su forma férrica fue monitoreada por medio de los cambios en la absorbancia del complejo de color rojo que se forma con la fenantrolina, observándose una reacción de pseudo primer orden  con una constante de velocidad de 0,050 ± 0,002 s-1. Las velocidades de oxidación fueron menores cuando se incorporó al medio un extracto de albedos de naranja, lo cual se asoció a la presencia de flavonoides. El efecto inhibidor presentó un orden de reacción igual a -1 con respecto a la concentración del extracto, manteniendo el primer orden en el catión divalente. Para el estudio de la cinética fueron muy valiosos el Método de los Estados Estacionarios, las ecuaciones integradas y la ecuación de Van´t Hoff . Esta experiencia puede ser muy útil para introducir a los estudiantes en los conceptos y modelos más importantes de la cinética química a nivel universitario. Resumen en inglés The kinetics study of iron(II)ophenantroline oxidation induced by HNO3 is proposed as a didactic experience for the course of chemical kinetics. Three didactic moments are included: First, review of related chemical concepts and design of the concept maps and the experiments. Experimental results are obtained and used to prove validity of proposed reaction mechanisms. Transformation of ferrous ion to ferric ion was followed by changes in absorbance of red colored ophenant (mas) roline complex. It was observed a pseudo first order kinetics with a velocity constant of 0,050 ± 0,002s-1. Oxidation rates were lower when an orange albedo extract was added to reaction mixture, which was associated with the presence of flavonoids in the natural extract. This inhibitory effect was associated with a reaction rate of -1 in natural extract concentration keeping the first order in the bivalent ion. Steady state method, integrated equations and Van´t Hoff method proven to be valuable for the kinetic study. The experience may be very useful to introduce the students in the most important concepts and models of the chemical kinetics at the university level.

Scientific Electronic Library Online (Spanish)

3

Transition state dynamics of OHF on several electronic states: Photodetachment spectrum of OHF- and conical intersections

González-Sánchez, Lola ; Gómez Carrasco, Susana ; Aguado, Alfredo ; Paniagua, Miguel ; Hernández, M. Luz

11 pages, 12 figures, 1 table.-- PACS nrs.: 33.80.Eh; 33.70.Ca; 31.50.Df; 31.50.Bc; 31.15.Ar; 82.20.Db; 33.20.Wr; 33.15.Bh. | Wave packet simulations of the photodetachment spectrum of OHF– are performed on several electronic adiabatic states, two triplets and four singlets of neutral OHF. The trans...

DRIVER (Spanish)

4

The role of exchange-correlation functionals in the potential energy surface and dynamics of N2 dissociation on W surfaces

Bocan, Gisela A. ; Díez Muiño, Ricardo ; Alducin Ochoa, Maite ; Busnengo, Heriberto Fabio ; Salin, Antoine

8 pages.-- PACS nrs.: 68.43.Mn, 82.65.+r, 82.30.Lp. | We study the dissociative adsorption of N2 on W(100) and W(110) by means of density functional theory and classical dynamics. Working with a full six-dimensional adiabatic potential energy surface (PES), we find that the theoretical results of th...

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5

Switching rates of multi-step reactions

Escudero, Carlos ; Kamenev, Alex

4 pages, 1 figure.-- PACS nrs.: 05.40.-a; 02.50.Ga; 64.60.My; 82.20.-w. | We consider a switching rate of a meta-stable reaction scheme, which includes reactions with arbitrary steps, e.g. kA --> (k+r)A. Employing WKB approximation, controlled by a large system size, we evaluate both the exponent an...

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6

Reactivity of highly cycled particles of CaO in a carbonation/calcination loop

Grasa, Gemma S. ; Abanades García, Juan Carlos ; Alonso Carreño, Mónica ; González García, Belén

7 pages, 8 figures.-- Available online May 24, 2007. | Calcium oxide can be an effective sorbent for separating CO2 at high temperatures. The carbonation reaction is the basis for several proposed high temperature CO2 capture systems when coupled with a calcination step to produce a pure CO2 stream....

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7

Quantum approaches for the insertion dynamics of the H(+) + D2 and D(+) + H2 reactive collisions

González Lezana, Tomás ; Aguado, Alfredo ; Paniagua, Miguel ; Roncero, Octavio

13 pages, 10 figures.-- PACS nrs.: 82.30.Fi; 82.30.Nr; 82.20.Pm; 82.20.Kh. | The H(+) + D2 and D(+) + H2 reactive collisions are studied using a recently proposed adiabatic potential energy surface of spectroscopic accuracy. The dynamics is studied using an exact wave packet method on the adiabatic ...

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8

Photodetachment spectrum of OHF-: Three-dimensional study of the heavy–light–heavy resonances

González-Sánchez, Lola ; Gómez Carrasco, Susana ; Aguado, Alfredo ; Paniagua, Miguel ; Hernández, M. Luz

12 pages, 14 figures, 1 table.-- PACS nrs.: 82.30.Cf; 82.20.Kh; 31.15.Ar; 33.15.Mt; 33.80.Gj; 31.25.Eb; 31.50.Bc. | In this work a simulation of the OHF- photodetachment spectrum is performed in a three-dimensional potential energy surface recently developed for OHF(3A''). The ground 2A' state poten...

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9

On the dynamics of the H(+) + D2(v=0, j=0) --> HD + D(+) reaction: A comparison between theory and experiment

Carmona-Novillo, Estela ; González Lezana, Tomás ; Roncero, Octavio ; Honvault, Pascal ; Launay, Jean-Michel

15 pages, 12 figures, 2 tables.-- PACS nr.: 82.30.Fi. | The H(+) + D2(v=0,j=0) --> HD + D(+) reaction has been theoretically investigated by means of a time independent exact quantum mechanical approach, a quantum wave packet calculation within an adiabatic centrifugal sudden approximation, a statis...

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10

Método de precipitación controlada de ZnO: estudio de las diferentes etapas mediante conductividad específica

Rodríguez Páez, Jorge Enrique; Moure Jiménez, Carlos; Durán Botia, Pedro; Fernández Lozano, José Francisco
1998-06-01

Digital.CSIC (Spain)

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Modelado de un gasificador estratificado de lecho móvil de biomasa, utilizando CFD/ CFD Modelling of an Open Core Downdraft Moving Bed Biomass Gasifier

Rogel-Ramírez, A.
2008-12-01

Resumen en español Este estudio describe un modelo numérico bidimensional, basado en Dinámica de Fluidos Computacional (CFD), desarrollado para simular el flujo y las reacciones que ocurren en un gasificador estratificado de flujos paralelos, en el que se resuelven ecuaciones de conservación Eulerianas para los componentes de la fase gaseosa, la fase sólida, velocidades y entalpías específicas. El modelo está basado en el código PHOENICS y representa una herramienta que puede ser ut (mas) ilizada en el análisis y diseño de gasificadores. En las reacciones globales homogéneas se consideran las contribuciones de la cinética química y la rapidez de mezclado, usando el modelo Eddy Brake-UP (EBU). La media harmónica de la cinética química y la transferencia de masa, determinan las velocidades globales de las reacciones heterogéneas entre el carbón activo y O2, CO2 y H2O. El efecto de la turbulencia en la fase gaseosa se determina usando el modelo k-s. El modelo proporciona información de la composición del gas, velocidades y temperaturas de salida y el comportamiento del reactor, y permite cambiar los parámetros de operación, y las propiedades de la alimentación. Finalmente, se comparan los valores predichos por el modelo con datos disponibles en la literatura, mostrando congruencia satisfactoria desde un punto de vista cualitativo. Resumen en inglés This paper contains the description of a bidimensional Computacional Fluid Dynamics (CFD), model developed to simulate the flow and reaction in a stratified downdraft biomass gasifier, whereby Eulerian conservation equations are solved for particle and gas phase components, velocities and specific enthalpies. The model is based on the PHOENICS package and represents a tool which can be used in gasifier analysis and design. Contributions of chemical kinetic and the mixing (mas) rate using the EBU approach are considered in the gas phase global homogeneous reactions. The harmonic blending of chemical kinetics and mass transfer effects, determine the global heterogeneous reactions between char and O2, CO2, and H2O. The turbulence effect in the gas phase is accounted by the standard k-s approach. The model provides information of the producer gas composition, velocities and temperature at the outlet, and allows different operating parameters and feed properties to be changed. Finally, a comparison with experimental data available in literature was done, which showed satisfactory agreement from a qualitative point of view, though further validation is required.

Scientific Electronic Library Online (Spanish)

14

Materiales carbonosos para el control de contaminantes orgánicos y atmosféricos. Diseño y rendimiento.

Mastral Lamarca, Ana María; Murillo Villuendas, Ramón; Navarro Lopez, María Victoria
2003-05-01

Digital.CSIC (Spain)

15

F+OH reactive collisions on new excited 3A'' and 3A' potential-energy surfaces

Gómez Carrasco, Susana ; Roncero, Octavio ; González-Sánchez, Lola ; Hernández, M. Luz ; Alvariño, José M.

13 pages, 10 figures, 5 tables.-- PACS nrs.: 82.30.Cf; 82.20.Kh; 82.20.Db; 82.20.Pm. | Global three-dimensional adiabatic potential-energy surfaces for the excited 2(3)A'' and 1(3)A' triplet states of OHF are obtained to study the F(2P)+OH(2Π)O(3P)+HF(1Σ+) reaction. Highly accurate ab initio calcula...

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16

Estudio cinético de la descomposición térmica de escombros lateríticos

López Gómez, Félix Antonio; Ramírez, M. C.; López Delgado, Aurora; Alguacil, Francisco José; Alonso Gámez, Manuel; Pons, J. A.
2006-10-08

Digital.CSIC (Spain)

17

Direct versus resonances mediated F+OH collisions on a new 3A'' potential energy surface

Gómez Carrasco, Susana ; González-Sánchez, Lola ; Aguado, Alfredo ; Roncero, Octavio ; Alvariño, José M.

14 pages, 13 figures, 4 tables.-- PACS nrs.: 82.30.Cf; 82.20.Kh; 31.15.Ar; 82.20.Fd; 33.80.Eh; 31.50.Df. | A theoretical study of the F(2P) + OH(2Π)HF(1Σ+) + O(3P) reactive collisions is carried out on a new global potential energy surface (PES) of the ground 3A'' adiabatic electronic state. The ab ...

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18

Determinación de la cinética de la oxidación catalítica del naftaleno

García Martínez,Tomás; Murillo Villuendas, Ramón; Puértolas Lacambra, Begoña
2009-02-01

Digital.CSIC (Spain)

19

Coupled diabatic potential energy surfaces for studying the nonadiabatic dynamics at conical intersections in angular resolved photodetachment simulations of OHF- --> OHF+e-

Gómez Carrasco, Susana ; Aguado, Alfredo ; Paniagua, Miguel ; Roncero, Octavio

16 pages, 14 figures, 1 table.-- PACS nrs.: 82.20.Kh; 82.30.Cf; 33.80.Eh; 82.20.Db; 82.20.Hf. | An energy-based method is proposed for the diabatization of the OH(2Π)+F(2P) --> O(3P)+HF(1Σ+) reaction. It is demonstrated that the diabatic representation obtained is regularized, i.e., the residual der...

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20

Coordinate transformation methods to calculate state-to-state reaction probabilities with wave packet treatments

Gómez Carrasco, Susana ; Roncero, Octavio

14 pages, 13 figures, 2 tables, 1 appendix.-- PACS nrs.: 82.30.Cf; 82.20.Rp. | A procedure for the transformation from reactant to product Jacobi coordinates is proposed, which is designed for the extraction of state-to-state reaction probabilities using a time-dependent method in a body-fixed frame...

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21

Collisional and photoinitiated reaction dynamics in the ground electronic state of Ca–HCl

Sanz, Cristina ; Avoird, Ad van der ; Roncero, Octavio

11 pages, 14 figures, 1 table.-- PACS nrs.: 82.30.Cf; 82.50.-m; 82.20.Kh; 82.30.Fi; 82.20.Rp; 82.20.Fd; 33.20.Ea; 33.15.Ry; 33.15.Dj; 82.30.Hk. | Ca+HCl(ν,j) reactive collisions were studied for different rovibrational states of the HCl reactant using wave-packet calculations in reactant Jacobi coor...

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22

Caracterización Estructural y Microestructural de Geles C-S-H

Martínez-Ramírez, Sagrario; Blanco Varela, M.ª Teresa
2008-01-01

Digital.CSIC (Spain)

24

Cinética de carbonatación de morteros experimentales de cal de tipo romano

Sánchez-Moral, S.; García Guinea, Javier; Luque, L.; González-Martín, R.; López-Arce, Paula
2004-09-30

Digital.CSIC (Spain)