A researcher accidentally spills benzene (C6H6, 78 g/mol) on the laboratory floor. Because benzene is a known carcinogen, the protocol is to evacuate the lab immediately. Because there are no spill kits and protective gear available, the researcher decides to let the benzene puddle evaporate. The lab ventilation system creates an air flow at velocity 1 m/s parallel to the surface of the benzene puddle. You can assume that the ventilation supplies a constant flow of fresh air (MWair = 29 g/mol). The puddle can be considered rectangular with a length L = 2 m, width W = 1 m and depth d = 1 mm. You may assume that the air and benzene puddle remain at room temperature (25C) throughout the evaporation process due to the large thermal mass of the building. At this temperature, the mass densities of benzene in the saturated vapor and liquid states are known to be 0.400 and 900 kg/m2, respectively, while the latent heat of evaporation is 400 kJ/kg. The aim of this problem is to estimate the time for the benzene to fully evaporate. As simplification, you may assume that during evaporation the depth of the benzene puddle remains uniform and slowly