Activation Volumes for the Hydration Reactions of Carbon Dioxide

2016 ◽  
Vol 69 (3) ◽  
pp. 262
Author(s):  
William Conway ◽  
Debra Fernandes ◽  
Carlos Rodríguez ◽  
Robert Burns ◽  
Manuel Martínez ◽  
...  
Keyword(s):  
Rate Constants ◽  
Global Analysis ◽  
Measurement Data ◽  
Current Data ◽  
Analysis Approach ◽  
Joint Analysis ◽  
Hydration Reaction ◽  
Kinetic Measurements ◽  
Decomposition Reactions ◽  
Reaction With Water

The hydration of CO2(aq) via reaction with H2O and OH– has been investigated using a high-pressure stopped flow apparatus, and the relevant rate constants for the reactions have been determined using a global analysis approach. The joint analysis of a series of kinetic measurements, for the formation and decomposition reactions, at a range of pressures from 400 to 1000 atm has been performed, and from the pressure dependence of the rate constants, the corresponding activation volume profiles determined for the two kinetic pathways. While a previous report exists for the hydration reaction with water, to our knowledge the activation volumes for the reaction of CO2 with hydroxide in this paper are the first to be reported in the literature. The extensive measurement data and robustness of the analysis approach, which additionally incorporates into, and corrects for, the effect of ionic strength on the kinetic data, positions the current data as the most reliable to date.

Rate constants of C5F10O decomposition reactions at temperatures of 300–3500 K

2018 ◽  
Vol 52 (3) ◽  
pp. 035202 ◽  
Author(s):  
Yuwei Fu ◽  
Mingzhe Rong ◽  
Xiaohua Wang ◽  
Aijun Yang
Keyword(s):  
Rate Constants ◽  
Decomposition Reactions

scholarly journals Mechanism of a Disassembly Driven Sensing System Studied by Stopped-Flow Kinetics

2021 ◽  
Author(s):  
Cara Gallo ◽  
Suma S. Thomas ◽  
Allison Selinger ◽  
Fraser Hof ◽  
Cornelia Bohne
Keyword(s):  
Steady State ◽  
Rate Constants ◽  
Artificial Saliva ◽  
Global Analysis ◽  
Dissociation Rate ◽  
Stopped Flow ◽  
Steady State Fluorescence ◽  
Saliva Analysis ◽  
Binding Isotherms ◽  
Dissociation Rate Constants

<div> Mechanistic studies were carried out on the kinetics for the assembly of a DimerDye (DD12) and the binding of the monomeric DimerDye (DD1) with nicotine in aqueous buffer and artificial saliva. DD12 is non-fluorescent, while monomeric DD1 and DD1-nicotine fluoresce. Binding isotherms were determined from steady-state fluorescence experiments. The report includes measurements of the steady-state fluorescence at pHs 2.2, 6.3 and 12.1, and stopped-flow kinetic data for the homodimerization forming DD12 and DD1-nicotine formation in buffer and artificial saliva. Analysis of the homodimerization kinetics led to the recovery of the association and dissociation rate constants for DD12. These rate constants were used in the global analysis for the coupled kinetics for DD1-nicotine formation, which led to the determination of the association and dissociation rate constants for nicotine binding to DD1.</div>

The acid-catalyzed decomposition of nitramide

1996 ◽  
Vol 74 (10) ◽  
pp. 1779-1783 ◽  
Author(s):  
Robin A. Cox
Keyword(s):  
Rate Constants ◽  
Activation Parameters ◽  
Cyclic Process ◽  
Dilute Acid ◽  
Acid Media ◽  
Dilute Acid Solution ◽  
Acid Catalyzed ◽  
Reaction With Water ◽  
Hydrochloric And Sulfuric Acids ◽  
Good Agreement

Much attention has been paid to the base-catalyzed decomposition of nitramide, but despite this it was not certain that a corresponding acid-catalyzed reaction even existed before the work described in this paper. The excess acidity method has been applied to nitramide decomposition rate constants obtained in aqueous perchloric acid media, and to a lesser extent in aqueous hydrochloric and sulfuric acids. This analysis shows that the decomposition in dilute acid solution is actually a base-catalyzed reaction, with water acting as the base (perhaps in a cyclic process involving two water molecules), with rate constants in good agreement with previous estimates. However, in more concentrated acid media a true acid-catalyzed reaction can be dissected out. Activation parameters are given for both mechanisms, and it is shown that the acid-catalyzed process is similar to the acid-catalyzed decomposition of alkylnitramines. In sulfuric acid the reaction is slightly faster than it is in the other acids, due to the presence of a base-catalyzed process involving sulfate. Key words: nitramide, excess acidity, acid-catalyzed, base-catalyzed, kinetics.

Oxidation of acetylferrocene and 1,1'-diacetylferrocene with cerium(IV) sulphate in sulphuric acid medium

1979 ◽  
Vol 44 (4) ◽  
pp. 1060-1069 ◽  
Author(s):  
Jaroslav Holeček ◽  
Karel Handlíř ◽  
Jiří Klikorka
Keyword(s):  
Acid Medium ◽  
Sulphuric Acid ◽  
Rate Constants ◽  
Redox Reactions ◽  
Acid Solutions ◽  
Oxidizing Agent ◽  
Ferrocene Derivatives ◽  
Kinetic Measurements ◽  
Complete Destruction ◽  
Sulphuric Acid Medium

Oxidation of acetylferrocene and 1,1'-diacetylferrocene with cerium(IV) sulphate has been studied in aqueous sulphuric acid solutions having the overall acidity H0 = +1 to -2. The first step in oxidation of the both ferrocene derivatives consists in a fast one-electron oxidation giving the corresponding unstable ferricenium cations. Their disappearance from the solution is connected with destruction of the sandwich molecule and further redox reactions. Complete destruction of acetylferrocene necessitates two equivalents of the oxidizing agent, the same reaction of 1,1'-diacetylferrocene proceeds by action of three equivalents of the oxidizing agent. On the basis of detailed kinetic measurements mechanism of the oxidation and destruction of the both derivatives has been suggested, and rate constants of decomposition of the sandwich molecules have been determined.

Rate constants for reactions of horseradish peroxidase compounds I and II with 4-substituted arylboronic acids

1994 ◽  
Vol 72 (10) ◽  
pp. 2159-2162 ◽  
Author(s):  
Weimei Sun ◽  
Xiaoying Ji ◽  
Larry J. Kricka ◽  
H. Brian Dunford
Keyword(s):  
Horseradish Peroxidase ◽  
Rate Constants ◽  
Compound I ◽  
Arylboronic Acid ◽  
Experimental Conditions ◽  
Kinetic Measurements ◽  
Arylboronic Acids ◽  
Total Ionic Strength ◽  
Compound Ii ◽  
Catalyzed Oxidation

The rate constants for the reactions of horseradish peroxidase compound I (k1) and compound II (k2) with three 4-substituted arylboronic acids, which enhance chemiluminescence in the horseradish peroxidase catalyzed oxidation of luminol by hydrogen peroxide, were determined at pH 8.6, total ionic strength 0.11 M, using stopped-flow kinetic measurements. For comparison, the rate constants of the reactions of 4-iodophenol with compounds I and II were also determined under the same experimental conditions. The three arylboronic acid derivatives and their rate constants are: 4-biphenylboronic acid, k1 = (1.21 ± 0.08) × 106 M−1 s−1, k2 = (4.6 ± 0.2) × 105 M−1 s−1; 4-bromophenylboronic acid, k1 = (5.5 ± 0.2) × 104 M−1 s−1, k2 = (3.6 ± 0.2) × 104 M−1 s−1; and 4-iodophenylboronic acid, k1 = (1.1 ± 0.2) × 105 M−1 s−1, k2 = (1.3 ± 0.1) × 104 M−1 s−1. 4-Biphenylboronic acid, which shows comparable luminescent enhancement to 4-iodophenol, has the highest reactivity in the reduction of both compounds I and II among the three arylboronic acid derivatives tested.

scholarly journals Validation of reactive gases and aerosols in the MACC global analysis and forecast system

2015 ◽  
Vol 8 (2) ◽  
pp. 1117-1169 ◽  
Author(s):  
H. Eskes ◽  
V. Huijnen ◽  
A. Arola ◽  
A. Benedictow ◽  
A.-M. Blechschmidt ◽  
...  
Keyword(s):  
Global Analysis ◽  
Measurement Data ◽  
Atmospheric Composition ◽  
Data Sets ◽  
Forecast System ◽  
Special Events ◽  
High Pollution ◽  
Reactive Gases ◽  
Monitoring Service

Abstract. The European MACC (Monitoring Atmospheric Composition and Climate) project is preparing the operational Copernicus Atmosphere Monitoring Service (CAMS), one of the services of the European Copernicus Programme on Earth observation and environmental services. MACC uses data assimilation to combine in-situ and remote sensing observations with global and regional models of atmospheric reactive gases, aerosols and greenhouse gases, and is based on the Integrated Forecast System of the ECMWF. The global component of the MACC service has a dedicated validation activity to document the quality of the atmospheric composition products. In this paper we discuss the approach to validation that has been developed over the past three years. Topics discussed are the validation requirements, the operational aspects, the measurement data sets used, the structure of the validation reports, the models and assimilation systems validated, the procedure to introduce new upgrades, and the scoring methods. One specific target of the MACC system concerns forecasting special events with high pollution concentrations. Such events receive extra attention in the validation process. Finally, a summary is provided of the results from the validation of the latest set of daily global analysis and forecast products from the MACC system reported in November 2014.

Rate Constants Deduced by Ab-Initio Calculations for Decomposition Reactions of CH3OCH2, C4H9OCH2 and C4H8OCH3 Radicals

2001 ◽  
Vol 215 (8) ◽  
Author(s):  
A. van der Loos ◽  
J. Vandooren ◽  
P.J. van Tiggelen ◽  
D. Peeters
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Theoretical Investigation ◽  
Rate Constants ◽  
Decomposition Reactions

The importance of thermal decompositions during the oxidation of methyl tertbutyl ether (MTBE) has motivated a theoretical investigation of reactions: C

Comparative Study of Drilling Riser Running/Retrieving Analysis Methodologies

2021 ◽  
Author(s):  
Leandro Vale ◽  
Conor Gallagher ◽  
Marcelo Souza ◽  
Daniel Carneiro
Keyword(s):  
Complex Geometry ◽  
Global Analysis ◽  
Fe Analysis ◽  
Analysis Approach ◽  
Harsh Environment ◽  
Local Response ◽  
Offshore Drilling ◽  
Global Response ◽  
Offshore Oil ◽  
Water Depths

Abstract Drilling risers are key components in offshore oil exploration and are present in most of the well construction phases (drilling, casing, cementing and completion). Mobile offshore drilling units can operate in different sites exposed to a range of environmental loadings and water depths. Global riser analyses based on the FE (finite element) method are performed to assess the system feasibility and operating envelopes. In harsh environment and ultradeep water scenarios, the riser running/retrieving operation is one of the most critical due to top-angle limits and riser stress as a result of either contact with the inside of the diverter housing/substructures or loading at the gimbal-spider (API-RP-16Q [1], ISO 13624-1 [2]). The use of beam-column elements is satisfactory for modelling the riser global response, however it may lead to result uncertainty in terms of local response associated with complex geometry, over-stress, stress concentration and contact modelling (DNV-ST-F201 [3], DNVGL-RP-F203 [4], ISO 13628-7 [5]). The objective of this paper is to compare riser analysis results from a global and a local FE analysis. This comparison is used to identify any limitations associated with the use of a global riser analysis approach for determining structural limits for the riser during deployment/retrieving operations. Several recommendations are also provided regarding the use of the global analysis approach.

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