4.4. A stream consisting of 44.6 mole% benzene and 55.4% toluene is fed at a constant rate to a process unit that produces two product streams, one a vapor and the other a liquid. The vapor flow rate is initially zero and asymptotically approaches half of the molar flow rate of the feed stream. Throughout this entire period, no material accumulates in the unit. When the vapor flow rate has become constant, the liquid is analyzed and found to be 28.0 mole% benzene. (a) Sketch a plot of liquid and vapor flow rates versus time from startup to when the flow rates become constant. (b) Is this process batch or continuous? Is it transient or steady-state before the vapor flow rate reaches its asymptotic limit? What about after it becomes constant? (c) For a feed rate of 100 mol/min, draw and fully label a flowchart for the process after the vapor flow rate has reached its limiting value, and then use balances to calculate the molar flow rate of the liquid and the composition of the vapor in mole fractions.

The vapor leaving the top of a distillation column goes to a condenser in which either total or partial condensation takes place. If a total condenser is used, a portion of the condensate is returned to the top of the column as refcr and the remaining liquid is taken off as the overhead product (or distillate). If a partial condenser is used, the liquid condensate is returned as reflux and the uncondensed vapor is taken off as the overhead product. The overhead product from an n-butane-n-pentane distillation column is 93 mole% butane. The temperature of the cooling fluid limits the condenser temperature to 39 °C or higher. REFLUX DRUM a) Using Raoult's law, estimate the minimum pressure at which the condenser can operate as a partial condenser (i.e., at which it can produce liquid for reflux) b) The production rate of overhead product is 50 kmol/h, and the mole ratio of reflux to overhead product is 2:1. Calculate the molar flow rates and compositions of the reflux stream and the vapor…

10. A container is separated into two halves by a membrane. Your lab partner assistant, Thurmond, is supposed to place a MgCl2 solution on side 1 and a NaCl solution on side 2. He is then supposed to measure the rate of water movement across the membrane. Unfortunately, Thurmond is not very good about keeping complete lab notes and he has forgotten to write down some data and calculations. Using your knowledge of osmosis, complete the following table. Temperature is 15°C and the hydraulic conductivity for the membrane is 0.4 ml/atm sec. MgCl2 Concentration on Side 1 NaCl Concentration on Side 2 80 mM Osmolarity on Side 1 Osmolarity on Side 2 Difference in osmotic pressure 60 mosM across the membrane Jy 0.95 ml/sec Reflection coefficient (ơ) Direction of water movement

Which of the following statements concerning corrosion is(are) true? For the false statements, correct them. a) Corrosion is an example of an electrolytic process. b) Corrosion of steel involves the reduction of iron coupled with the oxidation of oxygen. c) Steel rusts more easily in the dry (arid) Southwest states than in the humid Midwest states. d) Salting roads in the winter has the added benefit of hindering the corrosion of steel. e) The key to cathodic protection is to connect via a wire a metal more easily oxidized than iron to the steel surface to be protected.