课程名称︰质能平衡 Elementary pricinples of chemical process 课程性质︰选 课程教师︰蔡伟博 开课学院：工学院 开课系所︰化工系 考试日期（年月日）︰4/12/2011 考试时限（分钟）：120 是否需发放奖励金：yes 试题 : part 2 4. (15 points) A U-tube differential mercury manometer is connected between two pipes. One pipe contains carbon terachloride (sp.gr. 1.59) under a pressure of 10^3 kPa, and the other pipe contains oil (sp.gr. 0.80) under a pressure of 172 kPa, Find the manometer reading h in meters. Figure: -------- | CCl4 | ----------------------------------------------- =>a |- ----| || -------- || | | || ---------- =>b ============= Y | || "" | | || "" -------- ++ ---------- =>c "" ++ "" ++ ---------- =>d ++ ++ ++ +++++++++++++++++++++++++++ +++++++++++++++++++++++++++ distance between a,b = 2.5m , between b,c=1.5m, and between c,d=h in Y and "", is the oil, in ++ is the mercury, and in || is gas. 5. (20 points) A liquid mixture contains 60.0 wt% ethanol(E), 5.0 wt% of a dissolved solute (S), and the balance water. A stream of this mixture is fed to a continuous distillation column operating at stedy state. Product streams emerge at the top and the bottom of the column. The column design calls for the product stream to have equal mass flow rates and for the top stream to contain 90.0 wt% ethanol and no S. (A) Assume a basis of calculation, draw and fully label a process flowchart, do the degree of freedom analysis, and verify that all unknown stream flows and compositions can be calculated. (B) Calculate (i) the mass fraction of S in the bottom stream and (ii) the fraction of the ethanol in the feed that leaves in the bottom, product stream. if the process operations as designed. 6. (25 points) A common method used in manufacturing sodium hypochlorite bleach is by the reaction: Cl2+2NaOH ==> NaCl +NaOCl+H2O Chlorine gas is bubbled through an aqueous solution of sodium hydroxide, after which the desired product is separated from the sodium chloride. A water-NaOH solution that contains 1145 lb of pure NaOH is reacted with 851 lb of gaseous chlorine. The NaOCl formed weights 618 lb. (a) What was the limiting reactant? (b) What was the percentage excess of the excess reactand used? (c) What if the degree of completion of the reaction, expressed as the moles of NaOCl formed to the moles of NaOCl that would have formed if the reacted (勘误:reaction) had gone to completion? (d) What is the yield of NaOCl per amount of chlorine used (on a weight basis)? (e) What was the extent of reaction? Exam ends here. Appendix: Faters for unit conversions ------------------------------------------------------------------------------ Quality Equivalent values Mass 1 kg = 1000g = 0.001 metric ton = 2.20462 lbm = 35.27392 oz 1 lbm = 16oz = 5*10^(-4) ton = 453.593 g = 0.453593 kg Length 1 m = 100 cm = 1000 mm = 10^6 mocrons (um) = 10^10 angstroms (A) = 39.37 in. = 3.2808 ft = 1.0936 yd = 0.0006214 mile 1 ft = 12 in. = 1/3 yd = 0.3048 m = 30.48 cm Volume 1 m^3 = 1000 L = 10^6 cm^3 = 10^6 mL = 35.3145 ft^3 = 220.83 imperial gallons = 264.17 gal =1056.68 qt 1 ft^3 = 1728 in.^3 = 7.4805 gal = 0.028317 m^3 = 28.317 L = 28,317 cm^3 Force 1 N = 1 kg*m/s^2 = 10^5 dynes = 10^5 g*cm/s^2 = 0.22481 lbf 1 lbf = 32.174 lbm*ft/s^2 = 4.4482 N =4.4482*10^5 dynes Pressure 1 atm = 1.01325*10^5 N/m^2 (Pa) = 101.325 kPa = 1.01325 bar = 1.01325*10^6 dynes/cm^2 = 760 mmHg at 0 degree C(torr) = 10.333 m H2o at 4 degree C = 14.696 lbf/in^2 (psi) = 33.9 ft H2O at 4 degree C = 29.92 ft Hg at 0 degree C Energy 1 J = 1 N*m = 10^7 ergs = 10^7 dynes*cm = 2.778*10^(-7) kWh = 0.23901 cal = 0.7376 ft-lbf = 9.486*10^(-4) Btu Power 1 W = 1 J/s = 0.23901 cal/s = 0.7376 ft*lbf/s = 9.486*10^(-4) Btu/s = 1.341*10^(-3) hp ------------------------------------------------------------------------------ Example: the factor to convert grams to lbm is (2.20462 lbm/1000g)

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