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Reg. No. : ................................ Name : .....................................
Third Semester B.Tech. Degree Examination, November 2009 (2008 Scheme) Branch : Chemical Engineering 08.303 : PROCESS CALCULATIONS (H) Time : 3 Hours
Max. Marks : 100
Instructions : 1) Answer all questions. 2) Each question carries 4 marks. PART – A 1. The thermal conductivity of pure iron is 39 Btu/ (ft.hr.°F) and that of steel containing 1% C is 39 kcal/(m.h.°C). Which one is a good conductor of heat, iron or steel ? 2. Explain Vander Waals equation of state. 3. The molecular formula of an organic compound is C10H7Br. Find weight percentage of carbon, hydrogen and bromine in the solid. 4. Write briefly on Cox chast and Duhrings lines. 5. Explain proximate and ultimate analysis of coal. 6. Write material-balance-equations for a distillation operation explaining the terms used in the equations. 7. Explain the term limiting reactant giving examples. 8. State and explain Hes’s law of constant heat summation. 9. Define percentage humidity and relative humidity and explain the relation between the two. 10. Explain how heat of a reaction can be calculated from heat of formulation data. (10×4=40 Marks) P.T.O.
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PART – B Answer any one question from each Module. All questions carry equal marks. Module – I 11. The heat capacity of CO2 gas is given by Cp = 0.1978 + 1.059× 10–4t – 2.395× 10 –8 t2. Where Cp is in Btu /(1b°F) and t is in °F. Change the equation into the form in which Cp is in kJ/(k mol.K) and temperature in K. 20 OR 12. a) A flue gas has the following composition by volume. CO : 34.8%, H2 : 42%, CH4 : 0.4%, CO2 : 5.5%, O 2 : 0.2% and N2 : 17.1%. Calculate a) Composition in weight percent. b) Average molecular weight 12 c) Density at standard conditions in kg/m3. b) An aqueous solution of acetic acid of 35% concentration (by mass) has density 1.04 kg/h at 25° C. Find molarity, normality and molality of the solution.
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Module – II 13. a) Derive Clausius-Clapeyron equation going its limitations.
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b) At 360°K the vapor pressure of n-heptane and toluene are respectively 71.2 KPa and 48.9 KPa. Determine the composition of the liquid and vapor in equilibrium at 360 K and 65 KPa, if it is given that n-heptane and toluene form ideal solutions. 12 OR 14. An evaporator is fed continuously with 50000 kg/h of a solution containing 10% NaOH, 10% Nacl and the rest water by weight. During evaporation, water is removed as vapor and salt Nacl precipitates as crystals and is removed by filtration. The concentrated liquor leaving the evaporator contains 50%NaOH, 2% NaCl and the rest water. Determine : a) mass of water evaporated per hour b) mass of salt precipitated per hour c) mass of concentrated liquor produced per hour.
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Module – III 15. a) Explain bypass, recycle and purging operations with appropriate sketches.
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b) Ethyl alcohol is industrially produced by fermentation of molasses. A sample of molasses contains 45% (mass) fermentable sugars in the form of sucrose. The reactions in the fermenter are C12 H22 O11 + H2O C6 H12O6 + C6 H12O6 C6 H12 O6 2 C 2H5OH + 2 CO2. Calculate the theoretical production of rectified spirit (density 0.785 Kg/L) in liters per tonne of molasses.
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OR 16. Pure CO is mixed with 100 percent excess air and completely burnt at constant pressure. The reactants are originally at 400 K. Determine the heat added or remaned if the products leave at 600 K. The standard heat of reaction at 298 K is 282.99kJ permol CO burnt. The mean specific heats applicable are 29.10, 29.70, 29.10 and 20 41.45 J/mol K respectively for CO, O2, N2 and CO2.
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