Reaction of Hydrogen Atoms with Hydroxide Ions in High-Temperature and High-Pressure Water

Marin, Timothy W.; Jonah, Charles D.; Bartels, David M.

doi:10.1021/jp046737i

Cited by 25 publications

(27 citation statements)

References 37 publications

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“…A number of studies have been published in the last several years with the aim of providing the necessary fundamental information needed to model radiation chemistry in supercritical water. [10][11][12][13][14][15][16][17][18][19][20][21][22][23] Both reaction rates and radiation yields (G-values) for the primary free radicals • OH, H • , and e aq -are required, as well as for the recombination products H 2 and H 2 O 2 . Moreover, in reactor cores radiation is deposited both via γ radiation and energetic neutrons; 24 this paper represents the first in a series that will report G values from both /γ radiation and neutrons using the same detection methodology.…”

Section: Introductionmentioning

confidence: 99%

Neutron and β/γ Radiolysis of Water up to Supercritical Conditions. 1. β/γ Yields for H₂, H^• Atom, and Hydrated Electron

Janik

Janik²,

Bartels³

2007

J. Phys. Chem. A

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Yields for H2, H(.) atom, and hydrated electron production in beta/gamma radiolysis of water have been measured from room temperature up to 400 degrees C on a 250 bar isobar, and also as a function of pressure (density) at 380 and 400 degrees C. Radiolysis was carried out using a beam of 2-3 MeV electrons from a van de Graaff accelerator, and detection was by mass spectrometer analysis of gases sparged from the irradiated water. N2O was used as a specific scavenger for hydrated electrons giving N2 as product. Ethanol-d(6) was used to scavenge H(.) atoms, giving HD as a stable product. It is found that the hydrated electron yield decreases and the H(.) atom yield increases dramatically at lower densities in supercritical water, and the overall escape yield increases. The yield of molecular H2 increases with temperature and does not tend toward zero at low density, indicating that it is formed promptly rather than in spur recombination. A minimum in both the radical and H2 yields is observed around 0.4 kg/dm(3) density in supercritical water.

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Section: Introductionmentioning

confidence: 99%

Neutron and β/γ Radiolysis of Water up to Supercritical Conditions. 1. β/γ Yields for H₂, H^• Atom, and Hydrated Electron

Janik

Janik²,

Bartels³

2007

J. Phys. Chem. A

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“…is not yet measured, and so a second competition standard was needed to determine k4. The reaction of OHion with H • , as seen in reaction 7, was selected because the rate constant is well established at high temperature, including all temperatures in this study 18,19 .…”

Section: Thf-d8 + H • => • Thf-d7 + Hd (4)mentioning

confidence: 99%

Reaction rate of H atoms with N2O in hot water

Sargent

Sterniczuk

Bartels

2017

Radiation Physics and Chemistry

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The rate constant of H • atoms with N2O in water has been measured by a competition method up to 300 o C. Radiolysis with 2.5MeV electrons generated H • atoms, and the HD product from their reaction with deuterated tetrahydrofuran (THF-d8) was measured with mass spectroscopy. The concentration of THF-d8 was changed by an order of magnitude in the presence of 25mM N2O to obtain the ratio of rate constants. To determine the rate constant of H • with THF-d8, a similar competition vs. 0.2mM OHion was also measured. The reaction rate of H • with OHhas been accurately determined vs. temperature in previous work, allowing the two unknown rate constants to be deduced. Rate constant of H • with THF-d8 follows the Arrhenius law ln(k/M-1 s-1)= 27.33-(32.30 kJ/mol)/RT. Rate constant of H • with N2O follows the Arrhenius law ln(k/M-1 s-1)=24.50-(30.42 kJ/mol)/RT. In all likelihood, the N2O reaction proceeds via cis-HNNO • radical intermediate as in the gas phase, but with participation of a bridging water molecule in the 1,3 hydrogen shift to form N2 and • OH products.

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“…While kinetics of the corresponding reaction (1), which consists of a splitting of a water molecule, have not been well established, the reversed reaction (2) has long been investigated [5][6][7][8][9] and the relevant kinetic parameters determined by different groups. [10][11][12] Kinetic data for reactions of water anion with small radicals have also been tabulated. 13 As far as we are aware, the rate constant for reaction (1) evaluated at 298 K and 1 atm was indirectly determined from those of reaction (2), as for a unimolecular process, to be k(1) = 1040 s -1 .…”

Section: Introductionmentioning

confidence: 99%

A model study on the mechanism and kinetics for the dissociation of water anion

Huyen

Duong

Nguyen

et al. 2019

Int J of Chemical Kinetics

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Quantum chemical computations using both density functional theory (B3LYP functional) and wavefunction (MP2 and CCSD(T)) methods, with the 6-311++G(3df,2p) and aug-cc-pVnZ (n = D,T,Q) basis sets, in conjunction with a polarizable continuum model (PCM) method for treating structures in solution, were carried out to look again at a series of small negatively charged water species [(H 2 O) n ] •-. For each size n of [(H 2 O) n ] •in aqueous solution with n = 2, 3, and 4, two distinct structural motifs can be identified: a classical water radical anion formed by hydrogen bonds and a molecular pincer in which the excess electron is directly interacting with H atoms. In aqueous solution, both motifs have comparable energy content and likely coexist and compete for the ground state. Some water anion isomers can dissociate when interaction with a water molecule,through successive hydrogen transfers with moderate energy barriers. This reaction can also be regarded as a water-splitting process in which the H transfers involved take place mainly within a water trimer, whereas other water molecules tend to stabilize transition structures through microsolvation rather than direct participation. Calculated absolute rate constants for the reversed reaction H • (H 2 O) 2 + OH -(H 2 O) 2 → [(H 2 O) 4 ] • ‫-‬ + H 2 O with both H and D isotopes agree well with the experimentally evaluated counterpart and lend a kinetic support for the involvement of a tetramer unit. K E Y W O R D Sdissociation of water anions, hydrated electrons, reactions of water anions, water anions, water split by water anions 610

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Reaction of Hydrogen Atoms with Hydroxide Ions in High-Temperature and High-Pressure Water

Cited by 25 publications

References 37 publications

Neutron and β/γ Radiolysis of Water up to Supercritical Conditions. 1. β/γ Yields for H₂, H^• Atom, and Hydrated Electron

Neutron and β/γ Radiolysis of Water up to Supercritical Conditions. 1. β/γ Yields for H₂, H^• Atom, and Hydrated Electron

Reaction rate of H atoms with N2O in hot water

A model study on the mechanism and kinetics for the dissociation of water anion

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Reaction of Hydrogen Atoms with Hydroxide Ions in High-Temperature and High-Pressure Water

Cited by 25 publications

References 37 publications

Neutron and β/γ Radiolysis of Water up to Supercritical Conditions. 1. β/γ Yields for H2, H• Atom, and Hydrated Electron

Neutron and β/γ Radiolysis of Water up to Supercritical Conditions. 1. β/γ Yields for H2, H• Atom, and Hydrated Electron

Reaction rate of H atoms with N2O in hot water

A model study on the mechanism and kinetics for the dissociation of water anion

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Product

Resources

About

Neutron and β/γ Radiolysis of Water up to Supercritical Conditions. 1. β/γ Yields for H₂, H^• Atom, and Hydrated Electron

Neutron and β/γ Radiolysis of Water up to Supercritical Conditions. 1. β/γ Yields for H₂, H^• Atom, and Hydrated Electron