A mixture of benzene and dichloroethane is used to test the efficiency of a packed column that contains 10 ft of packing and operates adiabatically at atmospheric pressure. The liquid is charged to the reboiler, and the column is operated at total reflux until equilibrium is established. At equilibrium, liquid samples from the distillate and reboiler, as analyzed by refractive index, give the following compositions for benzene: xD = 0.653, xB = 0.298. Calculate the value of HETP in inches for this packing. What are the limitations on using this calculated value for design? Data for x-y at 1 atm (in benzene mole fractions) are