title: Reaction of hydrogen atoms with hydroxide ions in high-temperature and high-pressure water.
abstract: The rate constant for the reaction of hydrogen atoms (H(*)) with hydroxide ions (OH(-)) in aqueous solution has been measured from 100 to 300 degrees C by direct measurement of the hydrated electron ((e(-))(aq)) product growth rate. In combining these measurements with previous results, the reaction is observed to display Arrhenius behavior in two separate temperature regions, 3-100 and 100-330 degrees C, where the data above 100 degrees C show an obvious decrease in activation energy from 38.2 +/- 0.6 to 25.4 +/- 0.8 kJ mol(-1). The value of the rate constant is smaller than that estimated previously in the 200-300 degrees C range. The very unusual activation energy behavior of the forward and backward reactions is discussed in the context of transition state theory.
authors.affiliation: Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors.forename: Timothy W
authors.initials: TW
authors.lastname: Marin
authors.forename: Charles D
authors.initials: CD
authors.lastname: Jonah
authors.forename: David M
authors.initials: DM
authors.lastname: Bartels