AbstractDiffusion of water through slightly volatile hydrocarbon liquids can be described by dm/dt = –DA(dc/dx) where dm/dt is the rate of mass transport, A the area, dc/dx the concentration gradient, and D the diffusion coefficient. For dilute systems, D can be determined from an experimental evaluation of dm/dt, A, and dc/dx. In the experimental arrangement used, water diffuses through a layer of hydrocarbon lying fiat on a layer of water in a small beaker which is attached to a recording microbalance. The system is closed and maintained anhydrous with MgClO4. When steady‐state diffusion is attained, dm/dt is measured directly by the microbalance. Water diffuses from maximum concentration (water‐hydrocarbon interface) to zero concentration (hydrocarbon‐anhydrous air interface). Thus, the gradient dc/dx becomes –s/l where s is the solubility of water in the hydrocarbon, and l is the layer thickness. Therefore D = (dm/dt)l/(sA). Diffusion coefficients have been determined for water diffusing through n‐hexadecane and 2, 6, 10, 15, 19, 23‐hexamethyl tetracusane at five temperatures from 25–45°C. Results give a good fit in an Arrhenius plot. Diffusion activation energies are calculated as well as entropies of activation based on the Eyring absolute rate theory. Results are compared with data for the diffusion of water through polyethylene and polypropylene.

Schatzberg, P. (1965). Diffusion of water through hydrocarbon liquids. Journal of Polymer Science Part C: Polymer Symposia, 10(1), 87–92. Portico.