Diffusion of dioxygen in n-alkanes

The translational diffusion constant, D, of dioxygen, O-2, has been measure d in n-alkane solutions drawn through a microcapillary by reduced pressure. The passage of O-2 through the capillary has been monitored using its UV a bsorption at 190 nm. Data were taken in hexane, octane, decane, dodecane, t etradecane, and hexadecane. The diffusion constants decrease as the chain l ength increases and are not in agreement with the Stokes-Einstein relation. The data can be fitted to D/T = A/eta(p) with A = 1.27 x 10(-8) and p = 0. 562 (p = 1 for the Stokes-Einstein relation); T is the absolute temperature , and eta is the viscosity in P.