QUESTION III: (35 marka) Pertinent data on the binary system heptane-ethyl benzene are as follows: 0 0.08 0.185 0.251 0.333 0.487 0.651 0.788 0.914 1.0 0.233 0.428 0.514 0.608 0.729 0.834 0.904 0.963 1.0 y 0 A feed mixture composed of 42 mol heptane and 58 mol% ethyl benzene is to be fractionated to yield an overhead product of 97 mol% heptane and a residue of 99 mol% ethyl benzene. (a) Using a reflux ratio (LD) - 1.5, determine the number of equilibrium stages needed for a saturated liquid feed and a bubble point reflux by the McCabe-Thiele praphical method. (23 marks) (b) Compute the minimum reflux ratio (2 marks) (c) Determine the minimum number of equilibriums stages at total reflux (10 marka)