Agas stream with a flow rate of 15,000 mole/min at 25 c and atmospheric pressure with composition 5 mole % heptane, 95 mole % air is to be scrubbed by countercurrent contact with a nonvolatile absorption oil in a tower packed with 1.5 in raschig rings. exiting gas must be reduced to a heptane mole fraction equal to 0.01. entering oil is pure and has a flow rate of 4500 mole/min. heights of transfer units are as follows: hx = 0.20 m and h, = 0.55 m. the vapor pressure of heptane at 25 c is 46 mm hg. neglect evaporation of oil as well as dissolution of air in the liquid. raoult's law applies. perform material balances to accurately determine amounts of solute at the ends of the tower. due to the relative diluteness of the process you may, however, regard the flows of liquid and vapor to be approximately constant throughout the tower and the operating lines to be perfectly straight. the tower operates isothermally at 25 c and atmospheric pressure. what height of packing is required? (calculate via noy and hoy.)