CBE 40 Homework 5 Due September 30, 2020 15 points total Please review the course homework guidelines Reading for next week: D&R 2nd Ed. Section 3.4, D&R 1 s t Ed. Sections 3.14-3.15 Note: Only first three problems are graded. Problem 1 (5 Points) 1. Following a nuclear plant accident, groundwater is contaminated with a compound A. It can be removed from the water phase by extraction in an oily solvent; the A is transferred from the water to the oil as the two liquids flow through the extractor, as shown below. Whereas absorption is transfer from a gas phase to a liquid phase, extraction is transfer from one liquid phase to another liquid phase. To maintain two distinct liquid phases, the liquids must be immiscible. oil 1 water with A (1%) 2 oil with A oil phase water phase 3 water with A (0.1%) 4 Stream 1 is pure oil and stream 3 contains A. The extractor is long enough so that by the time the two phases exit (streams 3 and 4) they have reached equilibrium: no more A transfers into the oil. The equilibrium relationship for this particular system is given by the following empirical equation: xA,w = K xA,o Where xA,w and xA,o refer to the mass fractions of A in the water and oil phases, respectively, and K is an experimentally determined equilibrium constant. For this system K = 5.00. The flow rate of stream 2 is 100. kg/min, xA,2 = 0.010, and the extractor removes 90.% of the A from stream 2. (Hint: xA,4 = K x3,A) a) Calculate the flow rate of A in the oil phase leaving the extractor (stream 3). b) Calculate the flow rate of oil entering the extractor (stream 1). c) Now assume the extractor removes 99% of the A from stream 2. All other parameters remain the same and streams 3 and 4 are again in equilibrium. Calculate the flow rate of oil entering the extractor (stream 1) needed to achieve this. Give your answers in 2 significant figures. CBE 40 Homework 5 Due September 30, 2020 15 points total Problem 2 (5 Points): 2. D & R 2nd Ed 3.43 (E to X by two schemes) CBE 40 Homework 5 Due September 30, 2020 15 points total Problem 3 (5 Points): 3. A high temperature blast furnace converts iron oxide (from magnetite ore) to iron as part of the steel production process: Fe2O3 + 3C → 2Fe + 3CO After mixing 600. g/s of carbon (“coke”) with 2400. g/s of pure iron oxide (Fe2O3), the process produces 1200. g/s of pure iron. Report answers with 2 significant figures. Molecular weights are given below. a. Determine the percentage of excess carbon: _______% excess carbon b. Determine the percentage conversion of Fe2O3 to Fe: _____% conversion c. Calculate the flow rates of each substance in the product stream, in g/s. Molecular weights (g/mole) Fe2O3 160. C 12. Fe 55.8 CO 28 * The following three optional problems are for your practice and won’t be graded. Solutions will be posted for you to look at on your own. CBE 40 Homework 5 Due September 30, 2020 15 points total Optional Problem 4: 4. D & R 2nd Ed 3.17 (batches of elixir) CBE 40 Homework 5 Due September 30, 2020 15 points total Optional Problem 5: 5. A chemical process converts reactant A into product B in accordance with the process flow diagram below. How much of the reactant in stream 3 must be separated in order to have a flow rate of 95.0 mol/min for the product in stream 4 A 100. mol/min F1 F2 A A->B (80.0% conversion) F5 A Optional Problem 6: 6. D & R 2nd Ed 3.53 (A, B -> P, Q) F3 A B Separator X% A removed B 95.0 mol/min A 5 .00 mol/min F4