Dry gas containing 75 percent air and 25 percent ammonia vapor enters the bottom of a cylindrical packed absorption tower that is 2 ft in diameter. Nozzles in the top of the tower distribute water over the packing. A solution of ammonia in water is drawn from the bottom of the column, and scrubbed gas leaves the top. The gas enters at 80°F and 760 mm Hg pressure. It leaves at 60°F and 730 mm. The leaving gas contains, on the dry basis, 1.0 percent ammonia.

(a) If the entering gas flows through the empty bottom of the column at an average velocity (upward) of 1.5 ft/s, how many cubic feet of entering gas are treated per hour? 

(b) How many pounds of ammonia are absorbed per hour?