Water in the bottom of a narrow metal tube is held at a constant temperature of 20°C. The total pressure of air (assumed dry) is 101.325 kPa at a temperature of 20°C. Water evaporates and diffuses through the air in the tube and diffusion path of 0.5 ft long. Calculate the rate of evaporation in lb-mole/hr-ft^2 and kg-mole/m^2-s, taking the diffusivity of water vapor at 20°C and 1 atm pressure as 0.25 x 10^-4 m^2/s.