课程名称︰化学反应工程 课程性质︰必修 课程教师︰吴纪圣 开课学院：工学院 开课系所︰化工系 考试日期（年月日）︰103.04.01 考试时限（分钟）：120 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : The First Midterm of Reaction Engineering (Class 2) April 1, 2014 21:30~23:30 化工一 Close book 1. (20%) The gas-phase reaction, A → B + C is carried out isothermally in a 20 dm^3 constant-colume batch reactor. Twenty moles of pure A is initially placed in the reactor. The reactor is well mixed. (a) If the reaction is first order: -rA = k CA, with k = 0.865 min^-1, calculate the time necessary to reduce the number of moles of A in the reactor to 0.2 mol. (b) If the reaction is second order: -rA = k CA^2 with k = 2 dm^3/(mol-min), calculate the time necessary to consume 19.0 mol of A. (c) If the temperature is 127 ℃, what is the initial total pressure? What is the final total pressure assuming the reaction goes to complete. 2. (30%) The exothermic reaction, A → B + C, was carried out adiabatically and the following data recorded, X (conversion) 0 0.2 0.4 0.5 0.6 0.8 0.9 -rA (mol/dm^3-min) 10 16.67 50 50 50 12.5 9.09 The entering molar flow rate of A was 300 mol/min. (a) What are the PFR and CSTR columes necessary to achieve 40% conversion? (b) Over what range of conversions, would the CSTR and PFR reactor colume be identical? (c) What is the maximum conversion that can be achieved in a 10.5 dm^3 CSTR? 3. (20%) The rate laws for the following reactions were obtained at low temperatures. The reactions are highly exothermic and therefore reversible at high temperatures. Suggest a rate law of each reaction at high temperatures. (a) A → B, -rA = k CA^2 (b) A + 2B → 2D, -rA = k CA^(1/2) CB k PA PB (c) A + B → C + D, -rA = ----------------------- (1 + KA PA + KB PB)^2 4. (20%) Set up a stoichiometric table for the following reaction and express the concentration of each species in the reaction as a function of conversion. Evaluate all constants (e.g. ε, δ, θ...). Assume the reaction follows an elementary rate law, and write the reaction rate solely as a function of conversion, i.e. -rA = f(x). C2H6 → C2H4 + H2 Pure ethane enters the flow reactor at 7 bar and 1100K. How would you rate equation change if the reaction were to be carried out in a constant-colume batch reactor? 5. (20%) In 19th century, Henri Fabre found French ants busily bustled about their business on the hot days but were rather sluggish on cool days. The observed speeds are shown as followings, Running speed, m/hr 150 160 230 295 370 Temperature, ℃ 13 16 22 24 28 What activation energy represents this change in bustliness? ------------------------------------------------------------------------------ Gas constant: R = 8314 Pa-dm^3/(mol-K) or 82.06 X 10^-3 dm^3-bar/(mol-K), or 1.987 cal/mol-K Batch: NA0 dX/dt = -rA V CSTR: V = FA0 (Xout - Xin)/(-rA)out PFR: FA0 dX/dV = -rA --

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