Chemical Reaction Engineering GATE-1999

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Q 1: Overall order of reaction for which rate constant has units of (mol/L)–(3/2) sec–1 is





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Q 2: For the reaction A+B\rightarrow2B+C ,





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Q 3: The exit age distribution curve E(0) for an ideal CSTR with the average residence time τ, is given by





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Q 4: An endothermic second-order reaction is carried out in an adiabatic plug flow reactor. The rate of heat generation is





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Q 5: For the liquid phase zero-order irreversible reaction A → B, the conversion of A in a CSTR is found to be 0.3 at a space velocity of 0.1 min–1. What will be the conversion for a PFR with a space velocity of 0.2 mm–1? Assume that all the other operating conditions are the same for CSTR and PFR.





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Q 6: Consider the nth order irreversible liquid phase reaction A→ B. Which one of the following plots involving half-life of the reaction (t1/2) and the initial reactant concentration (CA0) gives a straight-line plot?





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Q 7: At a given value of E/R (ratio of activation energy and gas constant), the ratio of the rate constants at 500 K and 400 K is 2 if the Arrhenius law is used. What will be this ratio if transition state theory is used with the same value of E/R?





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Q 8: Two parallel first-order reactions A → B and A → C are taking place in the liquid phase in a well-mixed batch reactor. After 60 min of operation, 80 % of A has reacted while 2 moles of B per mole of C was detected in the reactor. Calculate the rate constants k1 and k2 for the two reactions. Assume that no B and C were initially present in the reactor.

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Q 9: An isothermal plug flow reactor is designed to give 80 % conversion of A for a second-order liquid phase reaction A → B. Pure A at a concentration 1 kmol/m3 is fed to the reactor at a flow rate of 5 m3/hr The rate constant for the reaction at a specified operating temperature is 0.5 m3/kmol h. When the reactor is actually operated based on this design, it was found that 30 % of the initial reactor behaved as a well-mixed reactor while the remaining behaved as a plug flow reactor. Calculate the conversion obtained in such a reactor.

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Q 10: For an exothermic reaction A → B, 90 kmol of B are to be produced while achieving 90 % conversion of A in an isothermal batch reactor operated at 500 K. The reaction is to be started with pure A at a concentration of 10 kmol/m3. Determine the volume of the reactor, duration of the batch operation, and the total heat removed during the isothermal operation. The heat of the reaction at 500 K is – 40 kJ/mol of A reacted. Following additional information is available to determine the order and rate constant of the reaction. Laboratory experiments conducted at 500 K with 1 kmol/m3 initial concentration of pure A showed that 20 % conversion is obtained in 20 min. while 50 % conversion is obtained in 80 min. The reaction is suspected to be either first or second order.

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