It is desired to estimate the mass-transfer coefficient kG in kg mol/s · m2 · Pa for water vapor in air at 338.6 K and 101.32 kPa flowing in a large duct past solids of different geometries. The velocity in the duct is 3.66 m/s. The water vapor concentration in the air is small, so the physical properties of air can be used. Water vapor is being transferred to the solids. Do this for the following geometries: a. A single 25.4-mm-diameter sphere. b. A packed bed of 25.4-mm spheres with ε = 0.35.