Example A continuous fractionating column is to be design to separate 30 lb/h of a mixture of 40 percent benzene and 60 percent toluene into an overhead product containing 97 percent benzene and a bottom product containing 98 percent toluene. These percentages are by weight. A reflux ratio of 3.5 mol to 1 mol of product is to be used. The molal latent heats of benzene and toluene are 7,360 and 7,960 cal/mol, respectively. Benzene and toluene form an ideal system with a relative volatility of about 2.5; the equilibrium curve is shown in Figure below. The feed has a boiling point of 95 C at a pressure of 1 atm. (a) Calculate the moles of overhead product and bottom product per hour. (b) Determine the number of ideal plate and the position of the feed plate: (i) if the feed is liquid and at its boiling point. (ii)if the feed is liquid and at 20 C (specific heat 0.44 cal/g.C) (iii) if the feed is a mixture of two-thirds vapor and one-third liquid. (c) If steam at 20 lb/in2 (1.36 atm) gauge used for heating, how muc steam is required per hour for each of the above three cases, neglecting heat losses and assuming the reflux is a saturated liquid ? (d) If cooling water enters the condenser at 25 C and leaves at 40 C, how much cooling water a required, in gallons per minute