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MID SEMESTER EXAMINATION

Faculty of Engineering

COURSE CODE : CHEM4005

LEVEL / SEMESTER : 4/1

COURSE TITLE : Reaction Engineering

ACADEMIC YEAR : 2010-2011

DATE : Monday, 06 December 2010

TIME : 09:00

DURATION : 2 Hours

MAXIMUM MARK : 100

COURSE COORDINATOR : Ahmed J. Ali Al-Dallal

STUDENT NAME

STUDENT ID GROUP NO

INSTRUCTIONS TO CANDIDATES

This question paper consists of3 pages only. AnswerALL questions. Write yourID, NAME and GROUP NUMBER clearly on allof your answer books.

Follow all examination rules.

Do not bring books or other related materials into theexamination room.

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Question 1: [40 marks]

The following elementary, reversible, gas-phase reaction takes place in a continuous stirred-tank

reactor (CSTR): A + B CThe following information are known:

- Forward reaction constant (kf) = 0.5 L/mol.s @ 50oC

- Equilibrium constant based on concentration (Kc) = 1.2 L/mol @ 50oC

- Total inlet flowrate is 10 L/min, with initial concentrations of CAO= 1M & CBO= 2M.

- The reactor is maintained under isothermal conditions at 50oC and at 1 atm.

i) Complete the following Stoichiometric Table Q1 for this reaction (fill in shaded areas):

Table Q1: Stoichiometric Table

ii) Write each species concentration in terms of conversion, XA.

iii) Solve for the equilibrium conversion at 500C.

iv)What CSTR volume is required to achieve 80% of the equilibrium conversion?

Question 2: [30 marks]

Pure gaseous (A) at about 3 atm and 30C, with initial concentration C A0=120 mmole/liter, is fed into a

1 liter CSTR at various flow rates. Reactant (A) decomposes in the reactor and the exit concentration ofA (CA) is measured for each flow rate (v0). The flow rate and concentration data are given in Table Q2.

The reaction is: A 3P

Table Q2: Flow rate and concentration data

v0 (Liter/min) 0.06 0.48 1.5 8.1

CA (mmole /Liter) 30 60 80 105

i) Write the mole balance for the CSTR where a 2nd order reaction is taking place.

ii) Show how you will plot the above data to obtain a straight line, and thus determine the

reaction rate constant (k).

Question 3: [30 marks]

The homogeneous gas decomposition of phosphine, 4 PH3(g) P4(g) +6 H2(g), proceeds at 649C

(rate constant = 10 hr-1) in a plug flow reactor operating at 649C and 460 kPa which produce 80%

conversion of a pure feed consisting of 40 mol/hr of pure phosphine.

i) Write the mole balance, rate law and stoichiometry equations for the system.

ii) Combine the three equations in (a).

iii) Estimate the volume of reactor.

Additional Data

R (Gas Constant) = 0.0821 atm.L/mol. K

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= 8.314 Pa.m3/ mol. K

STUDENT NAME

STUDENT ID GROUP NO

Graph Paper for Q2