Reply to comment on the possible role of the reaction H+H 2O→H 2+OH in the radiolysis of water at high temperatures

• Published in: Radiation physics and chemistry (Oxford, England : 1993) Vol. 79; no. 1; pp. 52 - 56
• Main Authors: Swiatla-Wojcik, Dorota, Buxton, George V.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 2010
• Subjects: Aqueous systems; Equilibrium constant; Gibbs energy; H atom; High temperature radiolysis; Hydrogen chemistry; Hydroxyl radical; Gibbs energy; Equilibrium constant; Aqueous systems; H atom; Hydrogen chemistry; High temperature radiolysis; Hydroxyl radical
• ISSN: 0969-806X; 1879-0895
• DOI: 10.1016/j.radphyschem.2009.07.024

In reply to “Comment on the possible role of reaction H+H 2O→H 2+OH in the radiolysis of water at high temperatures” (Bartels, 2009 Comment on the possible role of the reaction H+H 2O→H 2+OH in the radiolysis of water at high temperatures. Radiat. Phys. Chem. 78, 191–194) we present an alternative thermodynamic estimation of the reaction rate constant k. Based on the non-symmetric standard state convention we have calculated that the Gibbs energy of reaction Δ r G=57.26 kJ mol −1 and the reaction rate constant k=7.23×10 −5 M −1 s −1 at ambient temperature. Re-analysis of the thermodynamic estimation (Bartels, 2009 Comment on the possible role of the reaction H+H 2O→H 2+OH in the radiolysis of water at high temperatures. Radiat. Phys. Chem. 78, 191–194) showed that the upper limit for the rate constant at 573 K is k=1.75×10 4 M −1 s −1 compared to the value predicted by the diffusion-kinetic modelling (3.18±1.25)×10 4 M −1 s −1 (Swiatla-Wojcik, D., Buxton, G.V., 2005. On the possible role of the reaction H+H 2O→H 2+OH in the radiolysis of water at high temperatures. Radiat. Phys. Chem. 74(3–4), 210–219). The presented thermodynamic evaluation of k(573) is based on the assumption that k can be calculated from Δ r G and the rate constant of the reverse reaction which, as discussed, are both uncertain at high temperatures.