Biochem homework


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PROBLEM SET 1 *QUESTIONS ONLY - DUE: MONDAY, SEPTEMBER 19, 2011 DEFINING SYSTEMS Question 1: a) Define the terms: mass flow rate, volumetric flow rate, density, mass fraction b) What is conserved in a chemical reaction? c) Define closed, open and isolated systems. d) What is the material balance equation for an individual chemical species “A” in an open system? Which terms become zero if you have: a closed system, no reaction, or steady-state? MASS BALANCES Question 2: The kidneys carry out a separation process where blood enters at a rate of 1200 mL/min and is split into two streams: filtered blood and urine. We are specifically interested in the details of the separation of urea and a drug circulating in the patient’s blood by the patient. What is known is given in the figure. Find the unknown quantities in the filtered blood and urine streams. Find the unknown quantities in the filtered blood and urine streams. Assume density of all streams is the same as water = 1 kg/L. Note that 1 uM = 1 micromole per liter. *Question 3: You are preparing a mixture of methanol (MeOH) by combining two solutions of MeOH. More specifically, you are adding 200 g of solution A and 150 g of solution B. The mass fraction of MeOH in A is 0.4 and the mass fraction of MeOH in B is 0.7. What is the mass fraction MeOH in the final mixture C (see figure)? Question 4: You have designed a centrifuge system to separate cells from a solution. A mixture of water and cells enters the centrifuge system at a rate 1000 L/h and contains 500 mg cells/L. You can assume that the density is that of water (1 g/cm 3 ). The inlet stream or feed (F), is separated to a cell-free supernatant (S), and a pellet (P) consisting of a solution containing water and cells. The mass fraction of cells in the pellet is 0.5. Using the data in the figure, calculate the mass flow rates m P (g/hr) and m S (g/hr). Kidney Blood Filtered Blood Urine V B = 1200 mL/min C urea, B = 10 mg/dL C drug, B = 100 uM V F = ? C urea, F = ? C drug, F = 90 uM V U = 1.5 mL/min C urea, U = 500 mg/dL drug, U = ? C A 200 g x M, A = 0.400 150 g x M, B = 0.700 B Centrifuge Feed (F) Supernatant (S) Pellet (P) V F = 1000 L/h = 1.0 g/cm 3 C cells, F = 500 mg cells/L C cells, S = 0 X cells, P = 0.5 X water, P = 1- X cells, P = 0.5 F
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Question 5: Corn-steep liquor contains 2.5 wt% dextrose (i.e. the mass fraction of dextrose is 2.5/100 = 0.025) and 50 wt% water; the rest of the liquor stream is solids. Beet molasses contain 50 wt% sucrose, 1.0 wt% dextrose, and 18 wt% water; the rest of the molasses stream contains solids. Beet molasses is mixed with corn-steep liquor and water in a mixing tank to produce a dilute sugar mixture. The exit stream contains 2.0 wt% dextrose and 12.6 wt% sucrose, and is ready to be fed into a fermentation unit.
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This note was uploaded on 10/23/2011 for the course BIO 201 taught by Professor Frenkel/cervantes during the Spring '10 term at Rutgers.

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