Download GTU BE/B.Tech 2018 Winter 6th Sem New 2160506 Chemical Reaction Engineering I Question Paper

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GUJARAT TECHNOLOGICAL UNIVERSITY

BE - SEMESTER-VI (NEW) EXAMINATION - WINTER 2018

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Subject Code:2160506 Date:07/12/2018

Subject Name:Chemical Reaction Engineering - I

Time: 02:30 PM TO 05:00 PM Total Marks: 70

Instructions:

1. Attempt all questions.

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

Q.1

1. Classify reactions giving example of each 03
2. Differentiate elementary and non elementary reactions. 04

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3. List various theories of temperature dependency on rate of reaction and discuss any one in detail. 07

Q.2

1. Write a short note on ‘Variable volume batch reactor’ 03
2. The rate constant k at 27°C is 1.3x10⁷sec^-1 and its frequency factor is 2.785x10⁹ sec^-1. Determine its Entropy of activation and Enthalpy of activation. 04
3. Derive integrated rate expression for a liquid phase reaction 2A—> Products. 07

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OR

1. At certain temperature, the half-life period and initial concentration for a reaction are, 07
   t_1/2 =420 sec; C_ao = 0.405 mole/lit
   t_1/2 =275 sec; C_ao = 0.640 mole/lit
   Calculate the order of reaction and rate constant of the reaction.

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Q.3

1. Define space time and space velocity. 03
2. Derive performance equation for a ideal batch reactor 04
3. The reaction A—>B, r = k.C_a², occurs in CSTR with 90% Conversion, if k= 0.5 liter/mole min, C_a0= 2 mole/liter and v = 4 liter/ min, what residence time and reactor volume will be required? 07

OR

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1. Explain the method for searching the mechanism of chemical reaction. 03
2. Compare and contrast Integral method of analysis with differential method of analysis of kinetic data. 04
3. In a batch reactor, assuming first order kinetics, the conversion of a liquid reactant A is 70% in 13 min. Find the space time required to effect this conversion in a plug flow reactor and a mixed flow reactor. 07

Q.4

1. Discuss equal sized mixed flow reactors in series 03

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2. Derive performance equation for a CSTR. 04
3. A tubular reactor is to be designed for the thermal cracking of ethane to produce on a scale production of ethylene. The reaction is 07
   C₂H₆—> C₂H₄+ H₂
   The ethane fed at the rate of 10 tons/hr, is diluted with steam (0.5 mole of steam: 1 mole of Ethane) before entering the reactor to reduce amount of undesired products. The reaction is maintained at 900 °C and 1.4 atm total pressures. Reaction is first order irreversible and rate constant is 12.8 sec^-1 at 900°C. Calculate the volume of reactor required for 60% conversion of ethane per pass.

OR

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1. Show how fractional conversion X_A is related to temperature for any exothermic reaction being carried out in an adiabatic batch reactor. 03
2. Write a short note on Recycle reactor. 04
3. Derive the equation in terms of concentration for irreversible reactions in series for uni-molecular type first-order reaction such as A—>R—>S 07

Q.5

1. Discuss the effect of pressure on equilibrium conversion as predicted by thermodynamics keeping temperature fixed 03

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2. Discuss the method of maximization of rectangles applied to find the optimum intermediate conversion and optimum sizes of two mixed reactors in series 04
3. For the parallel decomposition of A where R is desired and C_ao= 1 What is the maximum C_R, we may expect in an isothermal operation in Batch Reactor , where the value of r_R = 1, r_S = 2C_a, r₁ = C_a? 07

OR

1. Discuss the effect of inert on equilibrium conversion as predicted by thermodynamics keeping temperature fixed 03
2. Explain optimum temperature progression in brief. 04

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3. Describe quantitative discussion about product distribution for reactions in parallel. 07

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