Self-diffusion and Structure of Liquid Water. III. Measurement of the Self-diffusion of Liquid Water with H², H³ and O¹⁸ as Tracers¹

Abstract

Vol. 75 bility of the tagged atom reacting with radicals which it has formed in losing its recoil energy.Alternative Theory of Product Formation Following (n,y) Activation.-Friedman and Libby and Fox and Libby11 have interpreted their important data on the products of the (n,y) reaction of bromine in liquid and solid propyl bromides to indicate that the parent molecule is the favored product when bonds are broken by high energy bromine atoms, and other products are favored when bonds are broken by recoiling atoms with energies only a few times greater than bond energies ("epithermal" energy range). We feel that there are a variety of theoretical reasons and types of experimental evidence which preclude the possibility that this subdivision of reaction probability which they have outlined is generally applicable. Some of these have been discussed earlier.7 They include a consideration of: (1) the differences in collisions and in fragmentation probability in condensed phases as compared to the gas phase;(2) the low probability of "head-on" collisions in which a recoil atom can (11) (a) L, Friedman and W. F.

Effect of Surface Pretreatment on the Underpaint Corrosion of AA2024-T3 at Various Temperatures

“…This activation energy also supports the notion that the rate is controlled by ETR instead of oxygen transport in the bulk electrolyte phase or through a polymer because signifi cantly lower activation energies are seen when the latter phenomena are controlling. [81][82][83][84][85][86] For example, the diffusion of water molecules through a bulk water phase in the polymer (polybutadiene) on steel is about 19.2 kJ/mol. 85 Ruggeri and Beck 34 calculated that the rate of diffusion through the tail was ten times that needed to support corrosion and more than ten times greater than the diffusion rate through many of the polymer coatings, which was supported by the observation of FFC, even when an O 2 impermeable metallic coating was used.…”

“…[81][82][83][84][85][86] For example, the diffusion of water molecules through a bulk water phase in the polymer (polybutadiene) on steel is about 19.2 kJ/mol. 85 Ruggeri and Beck 34 calculated that the rate of diffusion through the tail was ten times that needed to support corrosion and more than ten times greater than the diffusion rate through many of the polymer coatings, which was supported by the observation of FFC, even when an O 2 impermeable metallic coating was used. The activation energy for O 2 transport in an aqueous phase is quite low, changing only 1% to 2% per °C.…”

Nanometer‐Scale Water‐ and Proton‐Diffusion Heterogeneities across Water Channels in Polymer Electrolyte Membranes

“…The estimated D p for the proton near the sulfonic acid groups from the ξ ~270×10 −3 measured with 4-amino-TEMPO is ~ 2.8×10 −9 m 2 s −1 , which is a value comparable to D p ~2×10 −9 m 2 s −1 estimated from conductivity measurements at ~20 water molecules per sulfonic acid [9] While the absolute proton mobility is smaller than in bulk water, not surprisingly, the proton over water diffusivity measured with 4-amino-TEMPO in Nafion yields D p /D w ~ 5 comparable to what is known to be D p /D w = ~ 7 in bulk water with D p ~ 1.7×10 −8 m 2 s −1 [29][30][31] and D w ~2.4×10 −9 m 2 s −1 . [31,32] In contrast, D p /D w is only ~2 for the central region of the water channels as measured with 4-hydroxy-TEMPO.…”

Interstitial Water Chemistry of Deep Sea Drilling Project Site 503 and Its Implications for Submarine Hydrothermal Circulation

“…For an initial perturbation of concentration, in a 240-meter-long section, this time is about 2.2 × I0 6 yr., clearly less than the age of the basement sediment. A higher diffusion coefficient, as would be more appropriate for the diffusion of 18 O in H 2 O (Wang et al, 1953), results in a shorter time. Thus, the steadystate assumption seems to be valid for the major cations and 18 O.…”

“…O as a tracer (Wang et al, 1953) corrected by the formation factor and the average tem- perature (8°C) yields a value of about 15 × I0" 6 cm 2 /s. In this work, the value of 15 ×10~6 cm 2 /s has been used.…”