Kinetics of Coupled First-Order Reactions with Time-Dependent Rate Coefficients in Ternary Systems

1968 ◽  
Vol 7 (1) ◽  
pp. 125-131 ◽  
Author(s):  
Lothar Riekert ◽  
James Wei
Keyword(s):  
Ternary Systems ◽  
Time Dependent ◽  
Rate Coefficients ◽  
First Order ◽  
Dependent Rate ◽  
Kinetics Of

MODELLING NITROGEN PROCESSES IN SOIL: MATHEMATICAL DEVELOPMENT AND RELATIONSHIPS

1976 ◽  
Vol 56 (2) ◽  
pp. 71-78 ◽  
Author(s):  
D. R. CAMERON ◽  
C. G. KOWALENKO
Keyword(s):  
Time Dependent ◽  
Rate Coefficients ◽  
Nitrification Rate ◽  
Order Kinetic ◽  
Nitrogen Flow ◽  
First Order ◽  
Interaction Term ◽  
Flow Pathways ◽  
Adsorption Desorption ◽  
Temperature Water

A small subsystem model was developed to simulate the major nitrogen flow pathways in an unsaturated soil treated with ammonium sulphate. A nonlinear Freundlich equilibrium model and a Langmuir kinetic model were used to describe mathematically the adsorption–desorption of soluble NH4+ to the exchangeable and clay-fixed phases, respectively. Time dependent, microbial mediated first-order kinetic models were used to quantify the ammonification and nitrification processes. The subsystem model was then used as a research tool to derive ammonification and nitrification rate coefficients for a preceding incubation experiment conducted using different soil moisture contents and temperatures. The model yields reasonably good fits to the observed data. A subsequent regression analysis relating the coefficients to temperature and moisture pointed out the importance of the temperature–water content interaction term in quantifying microbial mediated processes.

Complex kinetic systems with time-dependent rate coefficients

1989 ◽  
Vol 44 (3) ◽  
pp. 185-191 ◽  
Author(s):  
J.C. Andre ◽  
F. Baros ◽  
J.M.G. Martinho
Keyword(s):  
Time Dependent ◽  
Rate Coefficients ◽  
Dependent Rate

The comparative chemistry of ammine and methylamine complexes of rhodium(III) and cobalt(III)

1977 ◽  
Vol 55 (17) ◽  
pp. 3166-3171 ◽  
Author(s):  
Thomas Wilson Swaddle
Keyword(s):  
Ionic Strength ◽  
Spectral Data ◽  
Electron Donor ◽  
Dissociation Constants ◽  
Base Hydrolysis ◽  
Acid Dissociation ◽  
Rate Coefficients ◽  
Acid Dissociation Constants ◽  
First Order ◽  
Kinetics Of

For the aquation of (CH3NH2)5RhCl2+, the first order rate coefficients are represented by ΔHaq* = 101.9 kJ mol−1 and ΔSaq* = −50.2 JK−1 mol−1 in 0.1 M HClO4, while for base hydrolysis the rate is first order in [(CH3NH2)5RhCl2+] and [OH−] at ionic strength 0.10 M and the rate coefficients (in M−1 s−1) are represented by ΔHOH*> = 108.6 kJ mol−1 and ΔSOH* = 74.1 J K−1 mol−1. Acid dissociation constants are reported for (RNH2)5MOH23+ (R = H or CH3; M = Rh or Co), and these, combined with spectral data, show CH3NH2 to be a poorer electron donor than NH3 in complexes of this type, contrary to expectations. The comparative kinetics of reactions of (RNH2)5MCl2+ support the assignment of an Ia mechanism to aquation when M = Rh or Cr, Id to aquation when M = Co, and Dcb for base hydrolysis in all these cases.

Chelating agents in high temperature aqueous chemistry. 1. The kinetics of the thermal decomposition of aqueous nitrilotriacetate (NTA), iminodiacetate (IDA), and N-methyliminodiacetate (MIDA)

1977 ◽  
Vol 55 (10) ◽  
pp. 1762-1769 ◽  
Author(s):  
Meindert Booy ◽  
Thomas Wilson Swaddle
Keyword(s):  
Chelating Agents ◽  
Nuclear Reactors ◽  
Rate Coefficients ◽  
Aqueous Mixtures ◽  
Hydrothermal Conditions ◽  
Good Thermal Stability ◽  
First Order ◽  
First Order Kinetics ◽  
Kinetics Of ◽  
Thermal Stability Of

Aqueous H3NTA, H2MIDA, H2IDA, and their anions decompose under hydrothermal conditions (400–580 K) according to first order kinetics by successive decarboxylations, oxidation by O2 being unimportant except at the highest temperatures. In the presence of added H+, the species H4NTA+ and, to a lesser extent, H3MIDA+ (but not H3IDA+), provide significant decomposition pathways through elimination of a —CH2COO— group (deacetylation). For HnNTA(3−n)−, first order rate coefficients kn for decomposition are k0 = 4.5 × 10−7, k1 ∼ 1 × 10−6, k2 ∼ 7 × 10−5, k3 = 2.1 × 10−4, and k4 = 1.0 × 10−2 s1, at 503 K and ionic strength 2.0 m, the spread in rates being due to differences in ΔS* rather than ΔH*. H2MIDA and H2IDA are comparable in reactivity to H3NTA, while their anions are much less reactive than the NTA species of the same charge. The good thermal stability of aqueous NTA commends it as a reagent for boiler servicing and for decontamination of water-cooled nuclear reactors. A potentiometric method for the estimation of mono-, di-, and tribasic aminoacids in aqueous mixtures of these is described.

scholarly journals The Kinetics of Joined Action of Triplet-Triplet Annihilation and First-Order Decay of Molecules in T1State in the Case of Nondominant First-Order Process: The Kinetic Model in the Case of Spatially Periodic Excitation

2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Paweł Borowicz ◽  
Bernhard Nickel
Keyword(s):  
Diffusion Coefficient ◽  
Kinetic Model ◽  
Periodic Pattern ◽  
Constructive Interference ◽  
First Order ◽  
Dependent Rate ◽  
Diffusion Controlled ◽  
Spatially Periodic ◽  
Kinetics Of ◽  
Triplet Triplet Annihilation

In this paper the model developed for estimation of the diffusion coefficient of the molecules in the triplet state is presented. The model is based on the intuitive modification of the Smoluchowski equation for the time-dependent rate parameter. Since the sample is irradiated with the spatially periodic pattern nonexponential effects can be expected in the areas of the constructive interference of the exciting laser beams. This nonexponential effects introduce changes in the observed kinetics of the diffusion-controlled triplet-triplet annihilation. Due to irradiation with so-called long excitation pulse these non-exponential effects are very weak, so they can be described with introducing very simple correction to the kinetic model described in the first paper of this series. The values of diffusion coefficient of anthracene are used to calculate the annihilation radius from the data for spatially homogeneous excitation.

Time-Dependent Rate Coefficients from Brownian Dynamics Simulations

1996 ◽  
Vol 100 (12) ◽  
pp. 5149-5154 ◽  
Author(s):  
Michael J. Potter ◽  
Brock Luty ◽  
Huan-Xiang Zhou ◽  
J. Andrew McCammon
Keyword(s):  
Brownian Dynamics ◽  
Time Dependent ◽  
Rate Coefficients ◽  
Dependent Rate ◽  
Dynamics Simulations ◽  
Brownian Dynamics Simulations
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