A laboratory apparatus to measure the diffusion coefï¬cient of vaporâ gas mixtures consists of a vertical, small-diameter column containing the liquid phase that evaporates into the gas ï¬owing over the mouth of the column. The gas ï¬ow rate is sufï¬cient to maintain a negligible vapor concentration at the exit plane. The column is 150 mm high, and the pressure and temperature in the chamber are maintained at 0.25 atm and 320 K, respectively. For calibration purposes, you've been asked to calculate the expected evaporation rate (kg/h-m2) for a test with water and air under the foregoing conditions, using the known value of DAB for the vapor-air mixture.