Atomic test of the Stokes-Einstein law. II. Diffusion of Xe through liquid hydrocarbons

The diffusion coefficient D has been measured for ¹³³Xe atoms diffusing through 12 liquid n-alkanes, n-pentane through n-hexadecane, at 20.0 ^∘{}C. The dependence of D (cm²/sec) on the viscosity {η} (P) was found to be D=(1.26±{}0.06)×{}10^-6{{η}}^{{{-}}0}$ $^{686±{}0.011}$ where ${{η}}20.0$ $_{^∘{}C}$ varies monotonically in these solvents from 0.235 cP (for n-${C}₅H₁₂) to 3.48 cP (for n-C₁₆{H}₃₄$). The observation that D is proportional to {η} to a negative power of magnitude near (2/3) is in agreement with other work on several different solute-solvent systems. Some ramifications of this dependence are suggested.