scholarly journals Single-Route Linear Catalytic Mechanism: A New, Kinetico-Thermodynamic Form of the Complex Reaction Rate

Symmetry ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1748 ◽  
Author(s):  
Gregory S. Yablonsky ◽  
Denis Constales ◽  
Guy B. Marin
Keyword(s):  
Reaction Rate ◽  
Catalytic Mechanism ◽  
Equilibrium Constants ◽  
Complex Reaction ◽  
Thermodynamic Factor ◽  
Kinetic And Thermodynamic Parameters ◽  
Kinetic Factor ◽  
Buffer Substance ◽  
Apparent Equilibrium ◽  
Thermodynamic Factors

For a complex catalytic reaction with a single-route linear mechanism, a new, kinetico-thermodynamic form of the steady-state reaction rate is obtained, and we show how its symmetries in terms of the kinetic and thermodynamic parameters allow better discerning their influence on the result. Its reciprocal is equal to the sum of n terms (n is the number of complex reaction steps), each of which is the product of a kinetic factor multiplied by a thermodynamic factor. The kinetic factor is the reciprocal apparent kinetic coefficient of the i-th step. The thermodynamic factor is a function of the apparent equilibrium constants of the i-th equilibrium subsystem, which includes the (n−1) other steps. This kinetico-thermodynamic form separates the kinetic and thermodynamic factors. The result is extended to the case of a buffer substance. It is promising for distinguishing the influence of kinetic and thermodynamic factors in the complex reaction rate. The developed theory is illustrated by examples taken from heterogeneous catalysis.

Enhanced Oxidation of Air Contaminants on an Ultra-Low Density UV-Accessible Aerogel Photocatalyst

1996 ◽  
Vol 454 ◽  
Author(s):  
M. Dreyer ◽  
G. K. Newman ◽  
L. Lobban ◽  
S. J. Kersey ◽  
R. Wang ◽  
...  
Keyword(s):  
Reaction Rate ◽  
Adsorption Equilibrium ◽  
Uv Light ◽  
Equilibrium Constants ◽  
Main Stream ◽  
Low Density ◽  
Air Contaminants ◽  
Reaction Rate Constants ◽  
Air Contaminant ◽  
Type Rate

ABSTRACTThis research developed new forms of photocatalysts that could potentially move photocatalytic degradation of air contaminants into the main stream of industrially used remediation technologies. Tests of the photocatalytic activity of the TiO2 aerogel catalysts have been carried out using both acetone and methane as the air contaminant. For comparison, the same tests were carried out on a standard (non-aerogel) anatase powder. Despite having very low crystallinity, the aerogel decontaminates the air far more effectively than an equal volume of the anatase powder which indicates that a much larger fraction of the aerogel is activated by the UV light. Experimental data were used to determine adsorption equilibrium constants for acetone, and to determine reaction rate constants assuming a Langmuir-Hinshelwood type rate expression.

scholarly journals “Transitivity”: A Code for Computing Kinetic and Related Parameters in Chemical Transformations and Transport Phenomena

Molecules ◽  
2019 ◽  
Vol 24 (19) ◽  
pp. 3478 ◽  
Author(s):  
Hugo G. Machado ◽  
Flávio O. Sanches-Neto ◽  
Nayara D. Coutinho ◽  
Kleber C. Mundim ◽  
Federico Palazzetti ◽  
...  
Keyword(s):  
Rate Constants ◽  
Reaction Rate ◽  
Reaction Rate Constant ◽  
State Theory ◽  
Chemical Transformations ◽  
Graphical Interface ◽  
Arrhenius Behavior ◽  
Reaction Rate Constants ◽  
Kinetic And Thermodynamic Parameters ◽  
Data Documentation

The Transitivity function, defined in terms of the reciprocal of the apparent activation energy, measures the propensity for a reaction to proceed and can provide a tool for implementing phenomenological kinetic models. Applications to systems which deviate from the Arrhenius law at low temperature encouraged the development of a user-friendly graphical interface for estimating the kinetic and thermodynamic parameters of physical and chemical processes. Here, we document the Transitivity code, written in Python, a free open-source code compatible with Windows, Linux and macOS platforms. Procedures are made available to evaluate the phenomenology of the temperature dependence of rate constants for processes from the Arrhenius and Transitivity plots. Reaction rate constants can be calculated by the traditional Transition-State Theory using a set of one-dimensional tunneling corrections (Bell (1935), Bell (1958), Skodje and Truhlar and, in particular, the deformed ( d -TST) approach). To account for the solvent effect on reaction rate constant, implementation is given of the Kramers and of Collins–Kimball formulations. An input file generator is provided to run various molecular dynamics approaches in CPMD code. Examples are worked out and made available for testing. The novelty of this code is its general scope and particular exploit of d -formulations to cope with non-Arrhenius behavior at low temperatures, a topic which is the focus of recent intense investigations. We expect that this code serves as a quick and practical tool for data documentation from electronic structure calculations: It presents a very intuitive graphical interface which we believe to provide an excellent working tool for researchers and as courseware to teach statistical thermodynamics, thermochemistry, kinetics, and related areas.

scholarly journals Adjustment of K' to varying pH and pMg for the creatine kinase, adenylate kinase and ATP hydrolysis equilibria permitting quantitative bioenergetic assessment.

1995 ◽  
Vol 198 (8) ◽  
pp. 1775-1782 ◽  
Author(s):  
E M Golding ◽  
W E Teague ◽  
G P Dobson
Keyword(s):  
Creatine Kinase ◽  
Gibbs Energy ◽  
Adenylate Kinase ◽  
Atp Hydrolysis ◽  
Equilibrium Constants ◽  
Binding Constants ◽  
Acid Dissociation ◽  
Free Magnesium ◽  
Apparent Equilibrium ◽  
Energy Of Formation

Physiologists and biochemists frequently ignore the importance of adjusting equilibrium constants to the ionic conditions of the cell prior to calculating a number of bioenergetic and kinetic parameters. The present study examines the effect of pH and free magnesium levels (free [Mg2+]) on the apparent equilibrium constants (K') of creatine kinase (ATP: creatine N-phosphotransferase; EC 2.7.3.2), adenylate kinase (ATP:AMP phosphotransferase; EC 2.7.4.3) and adenosinetriphosphatase (ATP phosphohydrolase; EC 3.6.1.3) reactions. We show how K' can be calculated using the equilibrium constant of a specified chemical reaction (Kref) and the appropriate acid-dissociation and Mg(2+)-binding constants at an ionic strength (I) of 0.25 mol l-1 and 38 degrees C. Substituting the experimentally determined intracellular pH and free [Mg2+] into the equation containing a known Kref and two variables, pH and free [Mg2+], enables K' to be calculated at the experimental ionic conditions. Knowledge of K' permits calculation of cytosolic phosphorylation ratio ([ATP]/[ADP][Pi]), cytosolic free [ADP], free [AMP], standard transformed Gibbs energy of formation (delta fG' degrees ATP) and the transformed Gibbs energy of the system (delta fG' ATP) for the biological system. Such information is vital for the quantification of organ and tissue bioenergetics under physiological and pathophysiological conditions.

scholarly journals A comparative analysis of empirical equations describing pressure dependence of equilibrium and reaction rate constants

2017 ◽  
Vol 95 (2) ◽  
pp. 149-161 ◽  
Author(s):  
Jacob Spooner ◽  
Noham Weinberg
Keyword(s):  
Experimental Data ◽  
Reaction Rate ◽  
Equilibrium Constants ◽  
Simulated Data ◽  
Diels Alder ◽  
Empirical Equations ◽  
Reaction Rate Constants ◽  
Analytical Functions ◽  
Experimental Errors ◽  
Reaction Volumes

General properties of the empirical analytical functions used to describe the effect of pressure on rate and equilibrium constants in solution are reviewed, and the effects of experimental errors on the accuracy of activation and reaction volumes predicted by these equations are compared. When the error levels are low (1%–2%) and pressure ranges are small (0–1 kbar), all functions perform well, but when fitting data with high error or extending to higher pressures, special care must be taken to obtain reliable results. Analysis of the results from fitting the equations to simulated data, as well as experimental data for Diels–Alder, Menshutkin, and methanolysis reactions, allows us to propose a set of general recommendations when using these equations as a tool for obtaining accurate activation and reaction volumes.

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