Diffusion in paraffin hydrocarbons. Diffusion of cyclohexylbromide in n-alkanes at 25°C

Abstract

The general applicability of the Stokes–Einstein relation for diffusion has been studied for the case of cyclohexylbromide diffusing in n-alkanes with special reference to the size relationship between the solute and solvent molecules.

The plot of D₀ against 1/η₀(D₀= mutual diffusion coefficient at infinite dilution, η₀= solvent viscosity) yields two straight lines with their point of intersection at about n-nonane (C₉). This appears to conform with a more generalized form of the Stokes–Einstein theory also taking into account particle size and molecular conformation for solvent molecules of increasing chain length.