γ Radiolysis of Liquids at High Pressures. VIII. Primary Yields at 8.7 kbar and Reactions of the Hydrated Electron with H2O and H3O+

Pressure invariance of the primary yields of water radiolysis (previously established for pressures up to 6.4 kbar) was shown to extend to 8.7 kbar in γ radiolysis of both neutral and 0.8N H2SO4 solutions. G(H2) was measured in γ radiolysis of the following deaerated solutions at 25° and pressures in the range 0–8.85 kbar: (a) 3 × 10−5M NaNO3 and 0.05M glucose (slightly alkaline); (b) 10−3M NaNO3, 2.3 × 10−4M HClO4, and 0.05M glucose. In solution (a) G(H2) is determined by a competition for eaq− between the diffusion-controlled Reaction [3], eaq−+NO3−→no H or H2, and Reaction [1], eaq−+H2O→H+OH−. In solution (b) the competition is between Reactions [3] and [2], eaq−+H3O+→H+H2O. All H are converted to H2 by reaction with glucose. With the assumption that pressure dependence of k3 is determined approximately by that of water viscosity, kinetic analysis of the results gives ΔV1‡ = − 14.3 ml mole−1 and ΔV2‡ ≈ 0 ml mole−1. From the value of ΔV2‡, the absolute partial molal volume of eaq− (based on a value of −5.4 ml mole−1 for H+) is estimated to be in the range 0–11.3 ml mole−1. With an estimated electrostriction contribution of −3 ml mole−1, the electron cavity volume is in the range 3–14 ml mole−1, as compared to about 100 ml mole−1 in liquid ammonia.