An open tank, 10 ft in diameter and containing benzene at 25oC, is exposed to air in such a manner that the surface of the liquid is covered with a stagnant air film estimated to be 0.2 in, thick. If the total pressure is 1 atrn and the air temperature is 25oC, what loss of material in pounds per day occurs from this tank? The specific gravity of benzene at 60°F is 0.877. The concentration of benzene at the outside of the film is so low that it may be neglected. For benzene, the vapor pressure at 25°C is 100 ton, and the diffusivity in air is 0.08 cm2/s.