* When a patient applies an eye drop for the treatment of glaucoma, the eye drop is transported to the tear system by a thin tear film. The eye drop diffuses to the eye at 25 C, through a thin tear film layer thickness of 0.07 mm, and the concentration of the eye drop in the tear (point 1 ) and the other boundary of the tear film (point 2) is 34 wt% (density p1=840 kg/m^3) and 9 wt% (density p1= 1030 kg/m^3), respectively. The diffusivity of eye drops in tears is 0.41x10^-9 m^2/s. Assuming a steady state and one boubndary impermeable to tear, calculate the rate of diffusion of eye drop across a film. The molecular weight of the eye drop and tear is 320 kg/kmol and 235 kg/mol, respectively.