Download GTU BE/B.Tech 2019 Winter 6th Sem New 2160506 Chemical Reaction Engineering I Question Paper

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GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER- VI (New) EXAMINATION - WINTER 2019

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Instructions:

1. Attempt all questions.

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2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.

MARKS

Q.1

1. Discuss variables affecting the rate of reaction. (03)

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2. A rocket engine burns a stoichiometric mixture of fuel (liquid hydrogen) in oxidant (liquid oxygen). The combustion chamber is cylindrical, 75 cm long and 60 cm in diameter, and the combustion process produces 108 kg/s of exhaust gases. If combustion is complete, find the rate of reaction of hydrogen and of oxygen. Hz + %2 O, —» H,O (04)
3. For a uni-molecular irreversible first order reaction in series A > R = S; Derive an expression for concentration of reactant A, intermediate product R and final product S as a function of time. Find the expression in terms of time when formation of R becomes maximum. (07)

Q.2

1. Differentiate molecularity and order of reaction. (03)
2. Give examples for catalytic homogeneous and heterogeneous reaction. (04)

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3. A homogeneous gas reaction A —® 3R has a reported rate at 215°C -ra = 102CA"2, [mol/liter sec] Find the space-time needed for 80% conversion of a 50% A, 50% inert feed to a plug flow-teactor operating at 215°C and 5 atm (Cao = 0.0625 mol/liter). (07)

   OR

4. What is an autocatalytic reaction? For an autocatalytic reaction A +R > R+R show that (07) M+XA) |

Q.3

1. Consider a feed Cao=100, Cpo =200, Cio =100 to a steady-flow reactor. The isothermal gas-phase reaction is A+3B —6R If Ca = 40 at the reactor exit, what is Cg, Xa, and Xg there? (03)

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2. Write in brief about Shifting order reaction. (04)
3. Reactant A decomposes in a batch reactor. A — Product The composition of A in the reactor is measured at various times. Find a rate equation to represent the data using integral method of analysis. (07)
   Time, t sec 0 20 40 60 120 180 300
   Conc. Ca 11 9 72 65 43 3 2
   mol/ litre

   OR

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Q.3

1. Explain Space time and space velocity in detail. (04)
2. Derive general equation showing the time required to achieve a conversion X4 for either isothermal or non-isothermal operation for ideal batch reactor with graphical representation. (07)

Q.4

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1. Define fractional yield and selectivity in detail. (03)
2. Explain Plug Flow Reactors in Series and in Parallel with equation. (04)
3. Discuss in detailed about product distribution for parallel reaction. (07)

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Q.4

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1. Liquid A decomposes by first-order kinetics, and in a batch reactor 50% of A is converted in a 5-minute run. How much longer would it take to reach 75% conversion? (03)
2. Discuss method of maximization of rectangles applied to find the optimum intermediate conversion and optimum sizes of two mixed flow reactors in series. (04)
3. Give detalil classification of reactions. (07)

Q.5

1. Give criteria for best Arrangement of a Set of Ideal Reactors. (03)

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2. Give comparison for mixed Vs. plug flow reactor. (04)
3. Derive equation for complete conversion for adiabatic operation. (07)

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Q.5

1. Write in brief about thermodynamic equilibrium constant. (03)

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2. Write physical significance of activation energy. Also discuss temperature dependency of activation energy using Arrhenius theory. (04)
3. Derive performance equation for Recycle reactor. (07)

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